diff --git a/src/OpenTelemetry.Api/.publicApi/Experimental/net462/PublicAPI.Unshipped.txt b/src/OpenTelemetry.Api/.publicApi/Experimental/net462/PublicAPI.Unshipped.txt
index 29b616ee92c..2c2dcbb59e2 100644
--- a/src/OpenTelemetry.Api/.publicApi/Experimental/net462/PublicAPI.Unshipped.txt
+++ b/src/OpenTelemetry.Api/.publicApi/Experimental/net462/PublicAPI.Unshipped.txt
@@ -1,5 +1,5 @@
 abstract OpenTelemetry.Logs.Logger.EmitLog(in OpenTelemetry.Logs.LogRecordData data, in OpenTelemetry.Logs.LogRecordAttributeList attributes) -> void
-abstract OpenTelemetry.Logs.LoggerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation!>! instrumentationFactory) -> OpenTelemetry.Logs.LoggerProviderBuilder!
+abstract OpenTelemetry.Logs.LoggerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Logs.LoggerProviderBuilder!
 OpenTelemetry.Logs.IDeferredLoggerProviderBuilder
 OpenTelemetry.Logs.IDeferredLoggerProviderBuilder.Configure(System.Action<System.IServiceProvider!, OpenTelemetry.Logs.LoggerProviderBuilder!>! configure) -> OpenTelemetry.Logs.LoggerProviderBuilder!
 OpenTelemetry.Logs.Logger
diff --git a/src/OpenTelemetry.Api/.publicApi/Experimental/net6.0/PublicAPI.Unshipped.txt b/src/OpenTelemetry.Api/.publicApi/Experimental/net6.0/PublicAPI.Unshipped.txt
index 29b616ee92c..2c2dcbb59e2 100644
--- a/src/OpenTelemetry.Api/.publicApi/Experimental/net6.0/PublicAPI.Unshipped.txt
+++ b/src/OpenTelemetry.Api/.publicApi/Experimental/net6.0/PublicAPI.Unshipped.txt
@@ -1,5 +1,5 @@
 abstract OpenTelemetry.Logs.Logger.EmitLog(in OpenTelemetry.Logs.LogRecordData data, in OpenTelemetry.Logs.LogRecordAttributeList attributes) -> void
-abstract OpenTelemetry.Logs.LoggerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation!>! instrumentationFactory) -> OpenTelemetry.Logs.LoggerProviderBuilder!
+abstract OpenTelemetry.Logs.LoggerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Logs.LoggerProviderBuilder!
 OpenTelemetry.Logs.IDeferredLoggerProviderBuilder
 OpenTelemetry.Logs.IDeferredLoggerProviderBuilder.Configure(System.Action<System.IServiceProvider!, OpenTelemetry.Logs.LoggerProviderBuilder!>! configure) -> OpenTelemetry.Logs.LoggerProviderBuilder!
 OpenTelemetry.Logs.Logger
diff --git a/src/OpenTelemetry.Api/.publicApi/Experimental/netstandard2.0/PublicAPI.Unshipped.txt b/src/OpenTelemetry.Api/.publicApi/Experimental/netstandard2.0/PublicAPI.Unshipped.txt
index 29b616ee92c..2c2dcbb59e2 100644
--- a/src/OpenTelemetry.Api/.publicApi/Experimental/netstandard2.0/PublicAPI.Unshipped.txt
+++ b/src/OpenTelemetry.Api/.publicApi/Experimental/netstandard2.0/PublicAPI.Unshipped.txt
@@ -1,5 +1,5 @@
 abstract OpenTelemetry.Logs.Logger.EmitLog(in OpenTelemetry.Logs.LogRecordData data, in OpenTelemetry.Logs.LogRecordAttributeList attributes) -> void
-abstract OpenTelemetry.Logs.LoggerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation!>! instrumentationFactory) -> OpenTelemetry.Logs.LoggerProviderBuilder!
+abstract OpenTelemetry.Logs.LoggerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Logs.LoggerProviderBuilder!
 OpenTelemetry.Logs.IDeferredLoggerProviderBuilder
 OpenTelemetry.Logs.IDeferredLoggerProviderBuilder.Configure(System.Action<System.IServiceProvider!, OpenTelemetry.Logs.LoggerProviderBuilder!>! configure) -> OpenTelemetry.Logs.LoggerProviderBuilder!
 OpenTelemetry.Logs.Logger
diff --git a/src/OpenTelemetry.Api/.publicApi/Stable/net462/PublicAPI.Shipped.txt b/src/OpenTelemetry.Api/.publicApi/Stable/net462/PublicAPI.Shipped.txt
index 15d0fffd707..3e799f099f6 100644
--- a/src/OpenTelemetry.Api/.publicApi/Stable/net462/PublicAPI.Shipped.txt
+++ b/src/OpenTelemetry.Api/.publicApi/Stable/net462/PublicAPI.Shipped.txt
@@ -2,11 +2,11 @@
 ~abstract OpenTelemetry.Context.Propagation.TextMapPropagator.Extract<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Func<T, string, System.Collections.Generic.IEnumerable<string>> getter) -> OpenTelemetry.Context.Propagation.PropagationContext
 ~abstract OpenTelemetry.Context.Propagation.TextMapPropagator.Fields.get -> System.Collections.Generic.ISet<string>
 ~abstract OpenTelemetry.Context.Propagation.TextMapPropagator.Inject<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Action<T, string, string> setter) -> void
-~abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation> instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder
-~abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddMeter(params string[] names) -> OpenTelemetry.Metrics.MeterProviderBuilder
-~abstract OpenTelemetry.Trace.TracerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation> instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder
-~abstract OpenTelemetry.Trace.TracerProviderBuilder.AddLegacySource(string operationName) -> OpenTelemetry.Trace.TracerProviderBuilder
-~abstract OpenTelemetry.Trace.TracerProviderBuilder.AddSource(params string[] names) -> OpenTelemetry.Trace.TracerProviderBuilder
+abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddMeter(params string![]! names) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+abstract OpenTelemetry.Trace.TracerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+abstract OpenTelemetry.Trace.TracerProviderBuilder.AddLegacySource(string! operationName) -> OpenTelemetry.Trace.TracerProviderBuilder!
+abstract OpenTelemetry.Trace.TracerProviderBuilder.AddSource(params string![]! names) -> OpenTelemetry.Trace.TracerProviderBuilder!
 ~OpenTelemetry.Baggage.GetBaggage() -> System.Collections.Generic.IReadOnlyDictionary<string, string>
 ~OpenTelemetry.Baggage.GetBaggage(string name) -> string
 ~OpenTelemetry.Baggage.GetEnumerator() -> System.Collections.Generic.Dictionary<string, string>.Enumerator
@@ -28,44 +28,44 @@
 ~OpenTelemetry.Context.ThreadLocalRuntimeContextSlot<T>.ThreadLocalRuntimeContextSlot(string name) -> void
 ~OpenTelemetry.Context.ThreadLocalRuntimeContextSlot<T>.Value.get -> object
 ~OpenTelemetry.Context.ThreadLocalRuntimeContextSlot<T>.Value.set -> void
-~OpenTelemetry.Metrics.IDeferredMeterProviderBuilder.Configure(System.Action<System.IServiceProvider, OpenTelemetry.Metrics.MeterProviderBuilder> configure) -> OpenTelemetry.Metrics.MeterProviderBuilder
-~OpenTelemetry.Trace.IDeferredTracerProviderBuilder.Configure(System.Action<System.IServiceProvider, OpenTelemetry.Trace.TracerProviderBuilder> configure) -> OpenTelemetry.Trace.TracerProviderBuilder
-~OpenTelemetry.Trace.Link.Attributes.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, object>>
-~OpenTelemetry.Trace.Link.Link(in OpenTelemetry.Trace.SpanContext spanContext, OpenTelemetry.Trace.SpanAttributes attributes) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, bool value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, bool[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, double value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, double[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, long value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, long[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, string value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, string[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.SpanAttributes(System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, object>> attributes) -> void
-~OpenTelemetry.Trace.SpanContext.SpanContext(in System.Diagnostics.ActivityTraceId traceId, in System.Diagnostics.ActivitySpanId spanId, System.Diagnostics.ActivityTraceFlags traceFlags, bool isRemote = false, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>> traceState = null) -> void
-~OpenTelemetry.Trace.SpanContext.TraceState.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>>
-~OpenTelemetry.Trace.Status.Description.get -> string
-~OpenTelemetry.Trace.Status.WithDescription(string description) -> OpenTelemetry.Trace.Status
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name, OpenTelemetry.Trace.SpanAttributes attributes) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name, System.DateTimeOffset timestamp) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name, System.DateTimeOffset timestamp, OpenTelemetry.Trace.SpanAttributes attributes) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.RecordException(string type, string message, string stacktrace) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.RecordException(System.Exception ex) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, bool value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, bool[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, double value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, double[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, int value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, int[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, string value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, string[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.UpdateName(string name) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartActiveSpan(string name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartActiveSpan(string name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan parentSpan, OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartRootSpan(string name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartSpan(string name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartSpan(string name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan parentSpan, OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TracerProvider.GetTracer(string name, string version = null) -> OpenTelemetry.Trace.Tracer
+OpenTelemetry.Metrics.IDeferredMeterProviderBuilder.Configure(System.Action<System.IServiceProvider!, OpenTelemetry.Metrics.MeterProviderBuilder!>! configure) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+OpenTelemetry.Trace.IDeferredTracerProviderBuilder.Configure(System.Action<System.IServiceProvider!, OpenTelemetry.Trace.TracerProviderBuilder!>! configure) -> OpenTelemetry.Trace.TracerProviderBuilder!
+OpenTelemetry.Trace.Link.Attributes.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, object?>>?
+OpenTelemetry.Trace.Link.Link(in OpenTelemetry.Trace.SpanContext spanContext, OpenTelemetry.Trace.SpanAttributes? attributes) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, bool value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, bool[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, double value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, double[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, long value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, long[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, string? value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, string?[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.SpanAttributes(System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, object?>>! attributes) -> void
+OpenTelemetry.Trace.SpanContext.SpanContext(in System.Diagnostics.ActivityTraceId traceId, in System.Diagnostics.ActivitySpanId spanId, System.Diagnostics.ActivityTraceFlags traceFlags, bool isRemote = false, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, string!>>? traceState = null) -> void
+OpenTelemetry.Trace.SpanContext.TraceState.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, string!>>!
+OpenTelemetry.Trace.Status.Description.get -> string?
+OpenTelemetry.Trace.Status.WithDescription(string? description) -> OpenTelemetry.Trace.Status
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name, OpenTelemetry.Trace.SpanAttributes? attributes) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name, System.DateTimeOffset timestamp) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name, System.DateTimeOffset timestamp, OpenTelemetry.Trace.SpanAttributes? attributes) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.RecordException(string? type, string? message, string? stacktrace) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.RecordException(System.Exception? ex) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, bool value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, bool[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, double value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, double[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, int value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, int[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, string? value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, string?[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.UpdateName(string! name) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartActiveSpan(string! name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartActiveSpan(string! name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan? parentSpan, OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartRootSpan(string! name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartSpan(string! name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartSpan(string! name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan? parentSpan, OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TracerProvider.GetTracer(string! name, string? version = null) -> OpenTelemetry.Trace.Tracer!
 ~override OpenTelemetry.Baggage.Equals(object obj) -> bool
 ~override OpenTelemetry.Context.Propagation.B3Propagator.Extract<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Func<T, string, System.Collections.Generic.IEnumerable<string>> getter) -> OpenTelemetry.Context.Propagation.PropagationContext
 ~override OpenTelemetry.Context.Propagation.B3Propagator.Fields.get -> System.Collections.Generic.ISet<string>
@@ -80,10 +80,10 @@
 ~override OpenTelemetry.Context.Propagation.TraceContextPropagator.Extract<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Func<T, string, System.Collections.Generic.IEnumerable<string>> getter) -> OpenTelemetry.Context.Propagation.PropagationContext
 ~override OpenTelemetry.Context.Propagation.TraceContextPropagator.Fields.get -> System.Collections.Generic.ISet<string>
 ~override OpenTelemetry.Context.Propagation.TraceContextPropagator.Inject<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Action<T, string, string> setter) -> void
-~override OpenTelemetry.Trace.Link.Equals(object obj) -> bool
-~override OpenTelemetry.Trace.SpanContext.Equals(object obj) -> bool
-~override OpenTelemetry.Trace.Status.Equals(object obj) -> bool
-~override OpenTelemetry.Trace.Status.ToString() -> string
+override OpenTelemetry.Trace.Link.Equals(object? obj) -> bool
+override OpenTelemetry.Trace.SpanContext.Equals(object? obj) -> bool
+override OpenTelemetry.Trace.Status.Equals(object? obj) -> bool
+override OpenTelemetry.Trace.Status.ToString() -> string!
 ~static OpenTelemetry.Baggage.Create(System.Collections.Generic.Dictionary<string, string> baggageItems = null) -> OpenTelemetry.Baggage
 ~static OpenTelemetry.Baggage.GetBaggage(OpenTelemetry.Baggage baggage = default(OpenTelemetry.Baggage)) -> System.Collections.Generic.IReadOnlyDictionary<string, string>
 ~static OpenTelemetry.Baggage.GetBaggage(string name, OpenTelemetry.Baggage baggage = default(OpenTelemetry.Baggage)) -> string
@@ -100,13 +100,13 @@
 ~static OpenTelemetry.Context.RuntimeContext.RegisterSlot<T>(string slotName) -> OpenTelemetry.Context.RuntimeContextSlot<T>
 ~static OpenTelemetry.Context.RuntimeContext.SetValue(string slotName, object value) -> void
 ~static OpenTelemetry.Context.RuntimeContext.SetValue<T>(string slotName, T value) -> void
-~static OpenTelemetry.Trace.ActivityExtensions.GetStatus(this System.Diagnostics.Activity activity) -> OpenTelemetry.Trace.Status
-~static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity activity, System.Exception ex) -> void
-~static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity activity, System.Exception ex, in System.Diagnostics.TagList tags) -> void
-~static OpenTelemetry.Trace.ActivityExtensions.SetStatus(this System.Diagnostics.Activity activity, OpenTelemetry.Trace.Status status) -> void
-~static OpenTelemetry.Trace.Tracer.CurrentSpan.get -> OpenTelemetry.Trace.TelemetrySpan
-~static OpenTelemetry.Trace.Tracer.WithSpan(OpenTelemetry.Trace.TelemetrySpan span) -> OpenTelemetry.Trace.TelemetrySpan
-~static OpenTelemetry.Trace.TracerProvider.Default.get -> OpenTelemetry.Trace.TracerProvider
+static OpenTelemetry.Trace.ActivityExtensions.GetStatus(this System.Diagnostics.Activity! activity) -> OpenTelemetry.Trace.Status
+static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity! activity, System.Exception? ex) -> void
+static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity! activity, System.Exception? ex, in System.Diagnostics.TagList tags) -> void
+static OpenTelemetry.Trace.ActivityExtensions.SetStatus(this System.Diagnostics.Activity! activity, OpenTelemetry.Trace.Status status) -> void
+static OpenTelemetry.Trace.Tracer.CurrentSpan.get -> OpenTelemetry.Trace.TelemetrySpan!
+static OpenTelemetry.Trace.Tracer.WithSpan(OpenTelemetry.Trace.TelemetrySpan? span) -> OpenTelemetry.Trace.TelemetrySpan?
+static OpenTelemetry.Trace.TracerProvider.Default.get -> OpenTelemetry.Trace.TracerProvider!
 abstract OpenTelemetry.Context.RuntimeContextSlot<T>.Get() -> T
 abstract OpenTelemetry.Context.RuntimeContextSlot<T>.Set(T value) -> void
 OpenTelemetry.ActivityContextExtensions
diff --git a/src/OpenTelemetry.Api/.publicApi/Stable/net6.0/PublicAPI.Shipped.txt b/src/OpenTelemetry.Api/.publicApi/Stable/net6.0/PublicAPI.Shipped.txt
index 62bcfd1fe02..6599b613303 100644
--- a/src/OpenTelemetry.Api/.publicApi/Stable/net6.0/PublicAPI.Shipped.txt
+++ b/src/OpenTelemetry.Api/.publicApi/Stable/net6.0/PublicAPI.Shipped.txt
@@ -2,11 +2,11 @@
 ~abstract OpenTelemetry.Context.Propagation.TextMapPropagator.Extract<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Func<T, string, System.Collections.Generic.IEnumerable<string>> getter) -> OpenTelemetry.Context.Propagation.PropagationContext
 ~abstract OpenTelemetry.Context.Propagation.TextMapPropagator.Fields.get -> System.Collections.Generic.ISet<string>
 ~abstract OpenTelemetry.Context.Propagation.TextMapPropagator.Inject<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Action<T, string, string> setter) -> void
-~abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation> instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder
-~abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddMeter(params string[] names) -> OpenTelemetry.Metrics.MeterProviderBuilder
-~abstract OpenTelemetry.Trace.TracerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation> instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder
-~abstract OpenTelemetry.Trace.TracerProviderBuilder.AddLegacySource(string operationName) -> OpenTelemetry.Trace.TracerProviderBuilder
-~abstract OpenTelemetry.Trace.TracerProviderBuilder.AddSource(params string[] names) -> OpenTelemetry.Trace.TracerProviderBuilder
+abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddMeter(params string![]! names) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+abstract OpenTelemetry.Trace.TracerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+abstract OpenTelemetry.Trace.TracerProviderBuilder.AddLegacySource(string! operationName) -> OpenTelemetry.Trace.TracerProviderBuilder!
+abstract OpenTelemetry.Trace.TracerProviderBuilder.AddSource(params string![]! names) -> OpenTelemetry.Trace.TracerProviderBuilder!
 ~OpenTelemetry.Baggage.GetBaggage() -> System.Collections.Generic.IReadOnlyDictionary<string, string>
 ~OpenTelemetry.Baggage.GetBaggage(string name) -> string
 ~OpenTelemetry.Baggage.GetEnumerator() -> System.Collections.Generic.Dictionary<string, string>.Enumerator
@@ -25,44 +25,44 @@
 ~OpenTelemetry.Context.ThreadLocalRuntimeContextSlot<T>.ThreadLocalRuntimeContextSlot(string name) -> void
 ~OpenTelemetry.Context.ThreadLocalRuntimeContextSlot<T>.Value.get -> object
 ~OpenTelemetry.Context.ThreadLocalRuntimeContextSlot<T>.Value.set -> void
-~OpenTelemetry.Metrics.IDeferredMeterProviderBuilder.Configure(System.Action<System.IServiceProvider, OpenTelemetry.Metrics.MeterProviderBuilder> configure) -> OpenTelemetry.Metrics.MeterProviderBuilder
-~OpenTelemetry.Trace.IDeferredTracerProviderBuilder.Configure(System.Action<System.IServiceProvider, OpenTelemetry.Trace.TracerProviderBuilder> configure) -> OpenTelemetry.Trace.TracerProviderBuilder
-~OpenTelemetry.Trace.Link.Attributes.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, object>>
-~OpenTelemetry.Trace.Link.Link(in OpenTelemetry.Trace.SpanContext spanContext, OpenTelemetry.Trace.SpanAttributes attributes) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, bool value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, bool[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, double value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, double[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, long value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, long[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, string value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, string[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.SpanAttributes(System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, object>> attributes) -> void
-~OpenTelemetry.Trace.SpanContext.SpanContext(in System.Diagnostics.ActivityTraceId traceId, in System.Diagnostics.ActivitySpanId spanId, System.Diagnostics.ActivityTraceFlags traceFlags, bool isRemote = false, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>> traceState = null) -> void
-~OpenTelemetry.Trace.SpanContext.TraceState.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>>
-~OpenTelemetry.Trace.Status.Description.get -> string
-~OpenTelemetry.Trace.Status.WithDescription(string description) -> OpenTelemetry.Trace.Status
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name, OpenTelemetry.Trace.SpanAttributes attributes) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name, System.DateTimeOffset timestamp) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name, System.DateTimeOffset timestamp, OpenTelemetry.Trace.SpanAttributes attributes) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.RecordException(string type, string message, string stacktrace) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.RecordException(System.Exception ex) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, bool value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, bool[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, double value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, double[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, int value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, int[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, string value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, string[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.UpdateName(string name) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartActiveSpan(string name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartActiveSpan(string name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan parentSpan, OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartRootSpan(string name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartSpan(string name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartSpan(string name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan parentSpan, OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TracerProvider.GetTracer(string name, string version = null) -> OpenTelemetry.Trace.Tracer
+OpenTelemetry.Metrics.IDeferredMeterProviderBuilder.Configure(System.Action<System.IServiceProvider!, OpenTelemetry.Metrics.MeterProviderBuilder!>! configure) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+OpenTelemetry.Trace.IDeferredTracerProviderBuilder.Configure(System.Action<System.IServiceProvider!, OpenTelemetry.Trace.TracerProviderBuilder!>! configure) -> OpenTelemetry.Trace.TracerProviderBuilder!
+OpenTelemetry.Trace.Link.Attributes.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, object?>>?
+OpenTelemetry.Trace.Link.Link(in OpenTelemetry.Trace.SpanContext spanContext, OpenTelemetry.Trace.SpanAttributes? attributes) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, bool value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, bool[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, double value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, double[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, long value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, long[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, string? value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, string?[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.SpanAttributes(System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, object?>>! attributes) -> void
+OpenTelemetry.Trace.SpanContext.SpanContext(in System.Diagnostics.ActivityTraceId traceId, in System.Diagnostics.ActivitySpanId spanId, System.Diagnostics.ActivityTraceFlags traceFlags, bool isRemote = false, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, string!>>? traceState = null) -> void
+OpenTelemetry.Trace.SpanContext.TraceState.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, string!>>!
+OpenTelemetry.Trace.Status.Description.get -> string?
+OpenTelemetry.Trace.Status.WithDescription(string? description) -> OpenTelemetry.Trace.Status
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name, OpenTelemetry.Trace.SpanAttributes? attributes) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name, System.DateTimeOffset timestamp) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name, System.DateTimeOffset timestamp, OpenTelemetry.Trace.SpanAttributes? attributes) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.RecordException(string? type, string? message, string? stacktrace) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.RecordException(System.Exception? ex) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, bool value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, bool[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, double value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, double[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, int value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, int[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, string? value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, string?[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.UpdateName(string! name) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartActiveSpan(string! name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartActiveSpan(string! name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan? parentSpan, OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartRootSpan(string! name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartSpan(string! name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartSpan(string! name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan? parentSpan, OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TracerProvider.GetTracer(string! name, string? version = null) -> OpenTelemetry.Trace.Tracer!
 ~override OpenTelemetry.Baggage.Equals(object obj) -> bool
 ~override OpenTelemetry.Context.Propagation.B3Propagator.Extract<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Func<T, string, System.Collections.Generic.IEnumerable<string>> getter) -> OpenTelemetry.Context.Propagation.PropagationContext
 ~override OpenTelemetry.Context.Propagation.B3Propagator.Fields.get -> System.Collections.Generic.ISet<string>
@@ -77,10 +77,10 @@
 ~override OpenTelemetry.Context.Propagation.TraceContextPropagator.Extract<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Func<T, string, System.Collections.Generic.IEnumerable<string>> getter) -> OpenTelemetry.Context.Propagation.PropagationContext
 ~override OpenTelemetry.Context.Propagation.TraceContextPropagator.Fields.get -> System.Collections.Generic.ISet<string>
 ~override OpenTelemetry.Context.Propagation.TraceContextPropagator.Inject<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Action<T, string, string> setter) -> void
-~override OpenTelemetry.Trace.Link.Equals(object obj) -> bool
-~override OpenTelemetry.Trace.SpanContext.Equals(object obj) -> bool
-~override OpenTelemetry.Trace.Status.Equals(object obj) -> bool
-~override OpenTelemetry.Trace.Status.ToString() -> string
+override OpenTelemetry.Trace.Link.Equals(object? obj) -> bool
+override OpenTelemetry.Trace.SpanContext.Equals(object? obj) -> bool
+override OpenTelemetry.Trace.Status.Equals(object? obj) -> bool
+override OpenTelemetry.Trace.Status.ToString() -> string!
 ~static OpenTelemetry.Baggage.Create(System.Collections.Generic.Dictionary<string, string> baggageItems = null) -> OpenTelemetry.Baggage
 ~static OpenTelemetry.Baggage.GetBaggage(OpenTelemetry.Baggage baggage = default(OpenTelemetry.Baggage)) -> System.Collections.Generic.IReadOnlyDictionary<string, string>
 ~static OpenTelemetry.Baggage.GetBaggage(string name, OpenTelemetry.Baggage baggage = default(OpenTelemetry.Baggage)) -> string
@@ -97,13 +97,13 @@
 ~static OpenTelemetry.Context.RuntimeContext.RegisterSlot<T>(string slotName) -> OpenTelemetry.Context.RuntimeContextSlot<T>
 ~static OpenTelemetry.Context.RuntimeContext.SetValue(string slotName, object value) -> void
 ~static OpenTelemetry.Context.RuntimeContext.SetValue<T>(string slotName, T value) -> void
-~static OpenTelemetry.Trace.ActivityExtensions.GetStatus(this System.Diagnostics.Activity activity) -> OpenTelemetry.Trace.Status
-~static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity activity, System.Exception ex) -> void
-~static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity activity, System.Exception ex, in System.Diagnostics.TagList tags) -> void
-~static OpenTelemetry.Trace.ActivityExtensions.SetStatus(this System.Diagnostics.Activity activity, OpenTelemetry.Trace.Status status) -> void
-~static OpenTelemetry.Trace.Tracer.CurrentSpan.get -> OpenTelemetry.Trace.TelemetrySpan
-~static OpenTelemetry.Trace.Tracer.WithSpan(OpenTelemetry.Trace.TelemetrySpan span) -> OpenTelemetry.Trace.TelemetrySpan
-~static OpenTelemetry.Trace.TracerProvider.Default.get -> OpenTelemetry.Trace.TracerProvider
+static OpenTelemetry.Trace.ActivityExtensions.GetStatus(this System.Diagnostics.Activity! activity) -> OpenTelemetry.Trace.Status
+static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity! activity, System.Exception? ex) -> void
+static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity! activity, System.Exception? ex, in System.Diagnostics.TagList tags) -> void
+static OpenTelemetry.Trace.ActivityExtensions.SetStatus(this System.Diagnostics.Activity! activity, OpenTelemetry.Trace.Status status) -> void
+static OpenTelemetry.Trace.Tracer.CurrentSpan.get -> OpenTelemetry.Trace.TelemetrySpan!
+static OpenTelemetry.Trace.Tracer.WithSpan(OpenTelemetry.Trace.TelemetrySpan? span) -> OpenTelemetry.Trace.TelemetrySpan?
+static OpenTelemetry.Trace.TracerProvider.Default.get -> OpenTelemetry.Trace.TracerProvider!
 abstract OpenTelemetry.Context.RuntimeContextSlot<T>.Get() -> T
 abstract OpenTelemetry.Context.RuntimeContextSlot<T>.Set(T value) -> void
 OpenTelemetry.ActivityContextExtensions
diff --git a/src/OpenTelemetry.Api/.publicApi/Stable/netstandard2.0/PublicAPI.Shipped.txt b/src/OpenTelemetry.Api/.publicApi/Stable/netstandard2.0/PublicAPI.Shipped.txt
index 62bcfd1fe02..6599b613303 100644
--- a/src/OpenTelemetry.Api/.publicApi/Stable/netstandard2.0/PublicAPI.Shipped.txt
+++ b/src/OpenTelemetry.Api/.publicApi/Stable/netstandard2.0/PublicAPI.Shipped.txt
@@ -2,11 +2,11 @@
 ~abstract OpenTelemetry.Context.Propagation.TextMapPropagator.Extract<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Func<T, string, System.Collections.Generic.IEnumerable<string>> getter) -> OpenTelemetry.Context.Propagation.PropagationContext
 ~abstract OpenTelemetry.Context.Propagation.TextMapPropagator.Fields.get -> System.Collections.Generic.ISet<string>
 ~abstract OpenTelemetry.Context.Propagation.TextMapPropagator.Inject<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Action<T, string, string> setter) -> void
-~abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation> instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder
-~abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddMeter(params string[] names) -> OpenTelemetry.Metrics.MeterProviderBuilder
-~abstract OpenTelemetry.Trace.TracerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation> instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder
-~abstract OpenTelemetry.Trace.TracerProviderBuilder.AddLegacySource(string operationName) -> OpenTelemetry.Trace.TracerProviderBuilder
-~abstract OpenTelemetry.Trace.TracerProviderBuilder.AddSource(params string[] names) -> OpenTelemetry.Trace.TracerProviderBuilder
+abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+abstract OpenTelemetry.Metrics.MeterProviderBuilder.AddMeter(params string![]! names) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+abstract OpenTelemetry.Trace.TracerProviderBuilder.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+abstract OpenTelemetry.Trace.TracerProviderBuilder.AddLegacySource(string! operationName) -> OpenTelemetry.Trace.TracerProviderBuilder!
+abstract OpenTelemetry.Trace.TracerProviderBuilder.AddSource(params string![]! names) -> OpenTelemetry.Trace.TracerProviderBuilder!
 ~OpenTelemetry.Baggage.GetBaggage() -> System.Collections.Generic.IReadOnlyDictionary<string, string>
 ~OpenTelemetry.Baggage.GetBaggage(string name) -> string
 ~OpenTelemetry.Baggage.GetEnumerator() -> System.Collections.Generic.Dictionary<string, string>.Enumerator
@@ -25,44 +25,44 @@
 ~OpenTelemetry.Context.ThreadLocalRuntimeContextSlot<T>.ThreadLocalRuntimeContextSlot(string name) -> void
 ~OpenTelemetry.Context.ThreadLocalRuntimeContextSlot<T>.Value.get -> object
 ~OpenTelemetry.Context.ThreadLocalRuntimeContextSlot<T>.Value.set -> void
-~OpenTelemetry.Metrics.IDeferredMeterProviderBuilder.Configure(System.Action<System.IServiceProvider, OpenTelemetry.Metrics.MeterProviderBuilder> configure) -> OpenTelemetry.Metrics.MeterProviderBuilder
-~OpenTelemetry.Trace.IDeferredTracerProviderBuilder.Configure(System.Action<System.IServiceProvider, OpenTelemetry.Trace.TracerProviderBuilder> configure) -> OpenTelemetry.Trace.TracerProviderBuilder
-~OpenTelemetry.Trace.Link.Attributes.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, object>>
-~OpenTelemetry.Trace.Link.Link(in OpenTelemetry.Trace.SpanContext spanContext, OpenTelemetry.Trace.SpanAttributes attributes) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, bool value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, bool[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, double value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, double[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, long value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, long[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, string value) -> void
-~OpenTelemetry.Trace.SpanAttributes.Add(string key, string[] values) -> void
-~OpenTelemetry.Trace.SpanAttributes.SpanAttributes(System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, object>> attributes) -> void
-~OpenTelemetry.Trace.SpanContext.SpanContext(in System.Diagnostics.ActivityTraceId traceId, in System.Diagnostics.ActivitySpanId spanId, System.Diagnostics.ActivityTraceFlags traceFlags, bool isRemote = false, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>> traceState = null) -> void
-~OpenTelemetry.Trace.SpanContext.TraceState.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>>
-~OpenTelemetry.Trace.Status.Description.get -> string
-~OpenTelemetry.Trace.Status.WithDescription(string description) -> OpenTelemetry.Trace.Status
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name, OpenTelemetry.Trace.SpanAttributes attributes) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name, System.DateTimeOffset timestamp) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.AddEvent(string name, System.DateTimeOffset timestamp, OpenTelemetry.Trace.SpanAttributes attributes) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.RecordException(string type, string message, string stacktrace) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.RecordException(System.Exception ex) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, bool value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, bool[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, double value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, double[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, int value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, int[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, string value) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string key, string[] values) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TelemetrySpan.UpdateName(string name) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartActiveSpan(string name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartActiveSpan(string name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan parentSpan, OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartRootSpan(string name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartSpan(string name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.Tracer.StartSpan(string name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan parentSpan, OpenTelemetry.Trace.SpanAttributes initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link> links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan
-~OpenTelemetry.Trace.TracerProvider.GetTracer(string name, string version = null) -> OpenTelemetry.Trace.Tracer
+OpenTelemetry.Metrics.IDeferredMeterProviderBuilder.Configure(System.Action<System.IServiceProvider!, OpenTelemetry.Metrics.MeterProviderBuilder!>! configure) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+OpenTelemetry.Trace.IDeferredTracerProviderBuilder.Configure(System.Action<System.IServiceProvider!, OpenTelemetry.Trace.TracerProviderBuilder!>! configure) -> OpenTelemetry.Trace.TracerProviderBuilder!
+OpenTelemetry.Trace.Link.Attributes.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, object?>>?
+OpenTelemetry.Trace.Link.Link(in OpenTelemetry.Trace.SpanContext spanContext, OpenTelemetry.Trace.SpanAttributes? attributes) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, bool value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, bool[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, double value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, double[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, long value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, long[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, string? value) -> void
+OpenTelemetry.Trace.SpanAttributes.Add(string! key, string?[]? values) -> void
+OpenTelemetry.Trace.SpanAttributes.SpanAttributes(System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, object?>>! attributes) -> void
+OpenTelemetry.Trace.SpanContext.SpanContext(in System.Diagnostics.ActivityTraceId traceId, in System.Diagnostics.ActivitySpanId spanId, System.Diagnostics.ActivityTraceFlags traceFlags, bool isRemote = false, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, string!>>? traceState = null) -> void
+OpenTelemetry.Trace.SpanContext.TraceState.get -> System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string!, string!>>!
+OpenTelemetry.Trace.Status.Description.get -> string?
+OpenTelemetry.Trace.Status.WithDescription(string? description) -> OpenTelemetry.Trace.Status
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name, OpenTelemetry.Trace.SpanAttributes? attributes) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name, System.DateTimeOffset timestamp) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.AddEvent(string! name, System.DateTimeOffset timestamp, OpenTelemetry.Trace.SpanAttributes? attributes) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.RecordException(string? type, string? message, string? stacktrace) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.RecordException(System.Exception? ex) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, bool value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, bool[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, double value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, double[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, int value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, int[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, string? value) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.SetAttribute(string! key, string?[]? values) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TelemetrySpan.UpdateName(string! name) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartActiveSpan(string! name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartActiveSpan(string! name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan? parentSpan, OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartRootSpan(string! name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartSpan(string! name, OpenTelemetry.Trace.SpanKind kind = OpenTelemetry.Trace.SpanKind.Internal, in OpenTelemetry.Trace.SpanContext parentContext = default(OpenTelemetry.Trace.SpanContext), OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.Tracer.StartSpan(string! name, OpenTelemetry.Trace.SpanKind kind, in OpenTelemetry.Trace.TelemetrySpan? parentSpan, OpenTelemetry.Trace.SpanAttributes? initialAttributes = null, System.Collections.Generic.IEnumerable<OpenTelemetry.Trace.Link>? links = null, System.DateTimeOffset startTime = default(System.DateTimeOffset)) -> OpenTelemetry.Trace.TelemetrySpan!
+OpenTelemetry.Trace.TracerProvider.GetTracer(string! name, string? version = null) -> OpenTelemetry.Trace.Tracer!
 ~override OpenTelemetry.Baggage.Equals(object obj) -> bool
 ~override OpenTelemetry.Context.Propagation.B3Propagator.Extract<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Func<T, string, System.Collections.Generic.IEnumerable<string>> getter) -> OpenTelemetry.Context.Propagation.PropagationContext
 ~override OpenTelemetry.Context.Propagation.B3Propagator.Fields.get -> System.Collections.Generic.ISet<string>
@@ -77,10 +77,10 @@
 ~override OpenTelemetry.Context.Propagation.TraceContextPropagator.Extract<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Func<T, string, System.Collections.Generic.IEnumerable<string>> getter) -> OpenTelemetry.Context.Propagation.PropagationContext
 ~override OpenTelemetry.Context.Propagation.TraceContextPropagator.Fields.get -> System.Collections.Generic.ISet<string>
 ~override OpenTelemetry.Context.Propagation.TraceContextPropagator.Inject<T>(OpenTelemetry.Context.Propagation.PropagationContext context, T carrier, System.Action<T, string, string> setter) -> void
-~override OpenTelemetry.Trace.Link.Equals(object obj) -> bool
-~override OpenTelemetry.Trace.SpanContext.Equals(object obj) -> bool
-~override OpenTelemetry.Trace.Status.Equals(object obj) -> bool
-~override OpenTelemetry.Trace.Status.ToString() -> string
+override OpenTelemetry.Trace.Link.Equals(object? obj) -> bool
+override OpenTelemetry.Trace.SpanContext.Equals(object? obj) -> bool
+override OpenTelemetry.Trace.Status.Equals(object? obj) -> bool
+override OpenTelemetry.Trace.Status.ToString() -> string!
 ~static OpenTelemetry.Baggage.Create(System.Collections.Generic.Dictionary<string, string> baggageItems = null) -> OpenTelemetry.Baggage
 ~static OpenTelemetry.Baggage.GetBaggage(OpenTelemetry.Baggage baggage = default(OpenTelemetry.Baggage)) -> System.Collections.Generic.IReadOnlyDictionary<string, string>
 ~static OpenTelemetry.Baggage.GetBaggage(string name, OpenTelemetry.Baggage baggage = default(OpenTelemetry.Baggage)) -> string
@@ -97,13 +97,13 @@
 ~static OpenTelemetry.Context.RuntimeContext.RegisterSlot<T>(string slotName) -> OpenTelemetry.Context.RuntimeContextSlot<T>
 ~static OpenTelemetry.Context.RuntimeContext.SetValue(string slotName, object value) -> void
 ~static OpenTelemetry.Context.RuntimeContext.SetValue<T>(string slotName, T value) -> void
-~static OpenTelemetry.Trace.ActivityExtensions.GetStatus(this System.Diagnostics.Activity activity) -> OpenTelemetry.Trace.Status
-~static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity activity, System.Exception ex) -> void
-~static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity activity, System.Exception ex, in System.Diagnostics.TagList tags) -> void
-~static OpenTelemetry.Trace.ActivityExtensions.SetStatus(this System.Diagnostics.Activity activity, OpenTelemetry.Trace.Status status) -> void
-~static OpenTelemetry.Trace.Tracer.CurrentSpan.get -> OpenTelemetry.Trace.TelemetrySpan
-~static OpenTelemetry.Trace.Tracer.WithSpan(OpenTelemetry.Trace.TelemetrySpan span) -> OpenTelemetry.Trace.TelemetrySpan
-~static OpenTelemetry.Trace.TracerProvider.Default.get -> OpenTelemetry.Trace.TracerProvider
+static OpenTelemetry.Trace.ActivityExtensions.GetStatus(this System.Diagnostics.Activity! activity) -> OpenTelemetry.Trace.Status
+static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity! activity, System.Exception? ex) -> void
+static OpenTelemetry.Trace.ActivityExtensions.RecordException(this System.Diagnostics.Activity! activity, System.Exception? ex, in System.Diagnostics.TagList tags) -> void
+static OpenTelemetry.Trace.ActivityExtensions.SetStatus(this System.Diagnostics.Activity! activity, OpenTelemetry.Trace.Status status) -> void
+static OpenTelemetry.Trace.Tracer.CurrentSpan.get -> OpenTelemetry.Trace.TelemetrySpan!
+static OpenTelemetry.Trace.Tracer.WithSpan(OpenTelemetry.Trace.TelemetrySpan? span) -> OpenTelemetry.Trace.TelemetrySpan?
+static OpenTelemetry.Trace.TracerProvider.Default.get -> OpenTelemetry.Trace.TracerProvider!
 abstract OpenTelemetry.Context.RuntimeContextSlot<T>.Get() -> T
 abstract OpenTelemetry.Context.RuntimeContextSlot<T>.Set(T value) -> void
 OpenTelemetry.ActivityContextExtensions
diff --git a/src/OpenTelemetry.Api/ActivityContextExtensions.cs b/src/OpenTelemetry.Api/ActivityContextExtensions.cs
index 47570613b3d..8d21c95a31c 100644
--- a/src/OpenTelemetry.Api/ActivityContextExtensions.cs
+++ b/src/OpenTelemetry.Api/ActivityContextExtensions.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 using System.Diagnostics;
 
 // The ActivityContext class is in the System.Diagnostics namespace.
diff --git a/src/OpenTelemetry.Api/BaseProvider.cs b/src/OpenTelemetry.Api/BaseProvider.cs
index 54df0bf5d15..1ccca7e13b4 100644
--- a/src/OpenTelemetry.Api/BaseProvider.cs
+++ b/src/OpenTelemetry.Api/BaseProvider.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 namespace OpenTelemetry;
 
 /// <summary>
diff --git a/src/OpenTelemetry.Api/Internal/OpenTelemetryApiEventSource.cs b/src/OpenTelemetry.Api/Internal/OpenTelemetryApiEventSource.cs
index fb13eb02dc0..dda27277d2b 100644
--- a/src/OpenTelemetry.Api/Internal/OpenTelemetryApiEventSource.cs
+++ b/src/OpenTelemetry.Api/Internal/OpenTelemetryApiEventSource.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 using System.Diagnostics.Tracing;
 
 namespace OpenTelemetry.Internal;
diff --git a/src/OpenTelemetry.Api/Logs/LoggerProviderBuilder.cs b/src/OpenTelemetry.Api/Logs/LoggerProviderBuilder.cs
index 76e7ad33ecc..a460e6e2598 100644
--- a/src/OpenTelemetry.Api/Logs/LoggerProviderBuilder.cs
+++ b/src/OpenTelemetry.Api/Logs/LoggerProviderBuilder.cs
@@ -47,5 +47,5 @@ protected LoggerProviderBuilder()
     /// <returns>Returns <see cref="LoggerProviderBuilder"/> for chaining.</returns>
     public abstract LoggerProviderBuilder AddInstrumentation<TInstrumentation>(
         Func<TInstrumentation> instrumentationFactory)
-        where TInstrumentation : class;
+        where TInstrumentation : class?;
 }
diff --git a/src/OpenTelemetry.Api/Metrics/IDeferredMeterProviderBuilder.cs b/src/OpenTelemetry.Api/Metrics/IDeferredMeterProviderBuilder.cs
index ca263d19d59..dded0bf1271 100644
--- a/src/OpenTelemetry.Api/Metrics/IDeferredMeterProviderBuilder.cs
+++ b/src/OpenTelemetry.Api/Metrics/IDeferredMeterProviderBuilder.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 namespace OpenTelemetry.Metrics;
 
 /// <summary>
diff --git a/src/OpenTelemetry.Api/Metrics/MeterProvider.cs b/src/OpenTelemetry.Api/Metrics/MeterProvider.cs
index 14cf4e3d714..ab66f629bc4 100644
--- a/src/OpenTelemetry.Api/Metrics/MeterProvider.cs
+++ b/src/OpenTelemetry.Api/Metrics/MeterProvider.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 namespace OpenTelemetry.Metrics;
 
 /// <summary>
diff --git a/src/OpenTelemetry.Api/Metrics/MeterProviderBuilder.cs b/src/OpenTelemetry.Api/Metrics/MeterProviderBuilder.cs
index 44e22a2c7f3..7ba999e91f7 100644
--- a/src/OpenTelemetry.Api/Metrics/MeterProviderBuilder.cs
+++ b/src/OpenTelemetry.Api/Metrics/MeterProviderBuilder.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 namespace OpenTelemetry.Metrics;
 
 /// <summary>
@@ -36,7 +38,7 @@ protected MeterProviderBuilder()
     /// <returns>Returns <see cref="MeterProviderBuilder"/> for chaining.</returns>
     public abstract MeterProviderBuilder AddInstrumentation<TInstrumentation>(
         Func<TInstrumentation> instrumentationFactory)
-        where TInstrumentation : class;
+        where TInstrumentation : class?;
 
     /// <summary>
     /// Adds given Meter names to the list of subscribed meters.
diff --git a/src/OpenTelemetry.Api/Trace/ActivityExtensions.cs b/src/OpenTelemetry.Api/Trace/ActivityExtensions.cs
index db23da16520..62419b821ad 100644
--- a/src/OpenTelemetry.Api/Trace/ActivityExtensions.cs
+++ b/src/OpenTelemetry.Api/Trace/ActivityExtensions.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using OpenTelemetry.Internal;
@@ -41,10 +43,11 @@ public static class ActivityExtensions
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static void SetStatus(this Activity activity, Status status)
     {
-        Debug.Assert(activity != null, "Activity should not be null");
-
-        activity.SetTag(SpanAttributeConstants.StatusCodeKey, StatusHelper.GetTagValueForStatusCode(status.StatusCode));
-        activity.SetTag(SpanAttributeConstants.StatusDescriptionKey, status.Description);
+        if (activity != null)
+        {
+            activity.SetTag(SpanAttributeConstants.StatusCodeKey, StatusHelper.GetTagValueForStatusCode(status.StatusCode));
+            activity.SetTag(SpanAttributeConstants.StatusDescriptionKey, status.Description);
+        }
     }
 
     /// <summary>
@@ -57,7 +60,8 @@ public static void SetStatus(this Activity activity, Status status)
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static Status GetStatus(this Activity activity)
     {
-        if (!activity.TryGetStatus(out StatusCode statusCode, out string statusDescription))
+        if (activity == null
+            || !activity.TryGetStatus(out var statusCode, out var statusDescription))
         {
             return Status.Unset;
         }
@@ -71,10 +75,8 @@ public static Status GetStatus(this Activity activity)
     /// <param name="activity">Activity instance.</param>
     /// <param name="ex">Exception to be recorded.</param>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static void RecordException(this Activity activity, Exception ex)
-    {
-        activity?.RecordException(ex, default);
-    }
+    public static void RecordException(this Activity activity, Exception? ex)
+        => RecordException(activity, ex, default);
 
     /// <summary>
     /// Adds an activity event containing information from the specified exception and additional tags.
@@ -83,7 +85,7 @@ public static void RecordException(this Activity activity, Exception ex)
     /// <param name="ex">Exception to be recorded.</param>
     /// <param name="tags">Additional tags to record on the event.</param>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static void RecordException(this Activity activity, Exception ex, in TagList tags)
+    public static void RecordException(this Activity activity, Exception? ex, in TagList tags)
     {
         if (ex == null || activity == null)
         {
diff --git a/src/OpenTelemetry.Api/Trace/IDeferredTracerProviderBuilder.cs b/src/OpenTelemetry.Api/Trace/IDeferredTracerProviderBuilder.cs
index bd54a427888..ec9aab9fd45 100644
--- a/src/OpenTelemetry.Api/Trace/IDeferredTracerProviderBuilder.cs
+++ b/src/OpenTelemetry.Api/Trace/IDeferredTracerProviderBuilder.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 namespace OpenTelemetry.Trace;
 
 /// <summary>
diff --git a/src/OpenTelemetry.Api/Trace/Link.cs b/src/OpenTelemetry.Api/Trace/Link.cs
index e329c5915b8..28ac1013065 100644
--- a/src/OpenTelemetry.Api/Trace/Link.cs
+++ b/src/OpenTelemetry.Api/Trace/Link.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 using System.Diagnostics;
 
 namespace OpenTelemetry.Trace;
@@ -30,8 +32,8 @@ namespace OpenTelemetry.Trace;
     /// </summary>
     /// <param name="spanContext">Span context of a linked span.</param>
     public Link(in SpanContext spanContext)
+        : this(in spanContext, attributes: null)
     {
-        this.ActivityLink = new ActivityLink(spanContext.ActivityContext);
     }
 
     /// <summary>
@@ -39,7 +41,7 @@ public Link(in SpanContext spanContext)
     /// </summary>
     /// <param name="spanContext">Span context of a linked span.</param>
     /// <param name="attributes">Link attributes.</param>
-    public Link(in SpanContext spanContext, SpanAttributes attributes)
+    public Link(in SpanContext spanContext, SpanAttributes? attributes)
     {
         this.ActivityLink = new ActivityLink(spanContext.ActivityContext, attributes?.Attributes);
     }
@@ -48,53 +50,39 @@ public Link(in SpanContext spanContext, SpanAttributes attributes)
     /// Gets the span context of a linked span.
     /// </summary>
     public SpanContext Context
-    {
-        get
-        {
-            return new SpanContext(this.ActivityLink.Context);
-        }
-    }
+        => new(this.ActivityLink.Context);
 
     /// <summary>
     /// Gets the collection of attributes associated with the link.
     /// </summary>
-    public IEnumerable<KeyValuePair<string, object>> Attributes
-    {
-        get
-        {
-            return this.ActivityLink.Tags;
-        }
-    }
+    public IEnumerable<KeyValuePair<string, object?>>? Attributes
+        => this.ActivityLink.Tags;
 
     /// <summary>
     /// Compare two <see cref="Link"/> for equality.
     /// </summary>
     /// <param name="link1">First link to compare.</param>
     /// <param name="link2">Second link to compare.</param>
-    public static bool operator ==(Link link1, Link link2) => link1.Equals(link2);
+    public static bool operator ==(Link link1, Link link2)
+        => link1.Equals(link2);
 
     /// <summary>
     /// Compare two <see cref="Link"/> for not equality.
     /// </summary>
     /// <param name="link1">First link to compare.</param>
     /// <param name="link2">Second link to compare.</param>
-    public static bool operator !=(Link link1, Link link2) => !link1.Equals(link2);
+    public static bool operator !=(Link link1, Link link2)
+        => !link1.Equals(link2);
 
     /// <inheritdoc />
-    public override bool Equals(object obj)
-    {
-        return (obj is Link link) && this.ActivityLink.Equals(link.ActivityLink);
-    }
+    public override bool Equals(object? obj)
+        => obj is Link link && this.ActivityLink.Equals(link.ActivityLink);
 
     /// <inheritdoc />
     public override int GetHashCode()
-    {
-        return this.ActivityLink.GetHashCode();
-    }
+        => this.ActivityLink.GetHashCode();
 
     /// <inheritdoc/>
     public bool Equals(Link other)
-    {
-        return this.ActivityLink.Equals(other.ActivityLink);
-    }
+        => this.ActivityLink.Equals(other.ActivityLink);
 }
diff --git a/src/OpenTelemetry.Api/Trace/SpanAttributes.cs b/src/OpenTelemetry.Api/Trace/SpanAttributes.cs
index a0da0b5a18e..07bf9f23c23 100644
--- a/src/OpenTelemetry.Api/Trace/SpanAttributes.cs
+++ b/src/OpenTelemetry.Api/Trace/SpanAttributes.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 using System.Diagnostics;
 using OpenTelemetry.Internal;
 
@@ -37,12 +39,12 @@ public SpanAttributes()
     /// Initializes a new instance of the <see cref="SpanAttributes"/> class.
     /// </summary>
     /// <param name="attributes">Initial attributes to store in the collection.</param>
-    public SpanAttributes(IEnumerable<KeyValuePair<string, object>> attributes)
+    public SpanAttributes(IEnumerable<KeyValuePair<string, object?>> attributes)
         : this()
     {
         Guard.ThrowIfNull(attributes);
 
-        foreach (KeyValuePair<string, object> kvp in attributes)
+        foreach (KeyValuePair<string, object?> kvp in attributes)
         {
             this.AddInternal(kvp.Key, kvp.Value);
         }
@@ -65,7 +67,7 @@ public void Add(string key, long value)
     /// </summary>
     /// <param name="key">Entry key.</param>
     /// <param name="value">Entry value.</param>
-    public void Add(string key, string value)
+    public void Add(string key, string? value)
     {
         this.AddInternal(key, value);
     }
@@ -95,7 +97,7 @@ public void Add(string key, double value)
     /// </summary>
     /// <param name="key">Entry key.</param>
     /// <param name="values">Entry value.</param>
-    public void Add(string key, long[] values)
+    public void Add(string key, long[]? values)
     {
         this.AddInternal(key, values);
     }
@@ -105,7 +107,7 @@ public void Add(string key, long[] values)
     /// </summary>
     /// <param name="key">Entry key.</param>
     /// <param name="values">Entry value.</param>
-    public void Add(string key, string[] values)
+    public void Add(string key, string?[]? values)
     {
         this.AddInternal(key, values);
     }
@@ -115,7 +117,7 @@ public void Add(string key, string[] values)
     /// </summary>
     /// <param name="key">Entry key.</param>
     /// <param name="values">Entry value.</param>
-    public void Add(string key, bool[] values)
+    public void Add(string key, bool[]? values)
     {
         this.AddInternal(key, values);
     }
@@ -125,12 +127,12 @@ public void Add(string key, bool[] values)
     /// </summary>
     /// <param name="key">Entry key.</param>
     /// <param name="values">Entry value.</param>
-    public void Add(string key, double[] values)
+    public void Add(string key, double[]? values)
     {
         this.AddInternal(key, values);
     }
 
-    private void AddInternal(string key, object value)
+    private void AddInternal(string key, object? value)
     {
         Guard.ThrowIfNull(key);
 
diff --git a/src/OpenTelemetry.Api/Trace/SpanContext.cs b/src/OpenTelemetry.Api/Trace/SpanContext.cs
index e0028db6a6e..2b01e33b9f7 100644
--- a/src/OpenTelemetry.Api/Trace/SpanContext.cs
+++ b/src/OpenTelemetry.Api/Trace/SpanContext.cs
@@ -13,6 +13,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 // </copyright>
+
+#nullable enable
+
 using System.Diagnostics;
 using OpenTelemetry.Context.Propagation;
 
@@ -39,7 +42,12 @@ namespace OpenTelemetry.Trace;
     /// associate with the <see cref="SpanContext"/>.</param>
     /// <param name="isRemote">The value indicating whether this <see cref="SpanContext"/> was propagated from the remote parent.</param>
     /// <param name="traceState">The traceState to associate with the <see cref="SpanContext"/>.</param>
-    public SpanContext(in ActivityTraceId traceId, in ActivitySpanId spanId, ActivityTraceFlags traceFlags, bool isRemote = false, IEnumerable<KeyValuePair<string, string>> traceState = null)
+    public SpanContext(
+        in ActivityTraceId traceId,
+        in ActivitySpanId spanId,
+        ActivityTraceFlags traceFlags,
+        bool isRemote = false,
+        IEnumerable<KeyValuePair<string, string>>? traceState = null)
     {
         this.ActivityContext = new ActivityContext(traceId, spanId, traceFlags, TraceStateUtilsNew.GetString(traceState), isRemote);
     }
@@ -57,46 +65,26 @@ public SpanContext(in ActivityContext activityContext)
     /// Gets the <see cref="ActivityTraceId"/> associated with this <see cref="SpanContext"/>.
     /// </summary>
     public ActivityTraceId TraceId
-    {
-        get
-        {
-            return this.ActivityContext.TraceId;
-        }
-    }
+        => this.ActivityContext.TraceId;
 
     /// <summary>
     /// Gets the <see cref="ActivitySpanId"/> associated with this <see cref="SpanContext"/>.
     /// </summary>
     public ActivitySpanId SpanId
-    {
-        get
-        {
-            return this.ActivityContext.SpanId;
-        }
-    }
+        => this.ActivityContext.SpanId;
 
     /// <summary>
     /// Gets the <see cref="ActivityTraceFlags"/> associated with this <see cref="SpanContext"/>.
     /// </summary>
     public ActivityTraceFlags TraceFlags
-    {
-        get
-        {
-            return this.ActivityContext.TraceFlags;
-        }
-    }
+        => this.ActivityContext.TraceFlags;
 
     /// <summary>
     /// Gets a value indicating whether this <see cref="SpanContext" />
     /// was propagated from a remote parent.
     /// </summary>
     public bool IsRemote
-    {
-        get
-        {
-            return this.ActivityContext.IsRemote;
-        }
-    }
+        => this.ActivityContext.IsRemote;
 
     /// <summary>
     /// Gets a value indicating whether this <see cref="SpanContext"/> is valid.
@@ -125,47 +113,40 @@ public IEnumerable<KeyValuePair<string, string>> TraceState
     /// Converts a <see cref="SpanContext"/> into an <see cref="ActivityContext"/>.
     /// </summary>
     /// <param name="spanContext"><see cref="SpanContext"/> source.</param>
-    public static implicit operator ActivityContext(SpanContext spanContext) => spanContext.ActivityContext;
+    public static implicit operator ActivityContext(SpanContext spanContext)
+        => spanContext.ActivityContext;
 
     /// <summary>
     /// Compare two <see cref="SpanContext"/> for equality.
     /// </summary>
     /// <param name="spanContext1">First SpanContext to compare.</param>
     /// <param name="spanContext2">Second SpanContext to compare.</param>
-    public static bool operator ==(SpanContext spanContext1, SpanContext spanContext2) => spanContext1.Equals(spanContext2);
+    public static bool operator ==(SpanContext spanContext1, SpanContext spanContext2)
+        => spanContext1.Equals(spanContext2);
 
     /// <summary>
     /// Compare two <see cref="SpanContext"/> for not equality.
     /// </summary>
     /// <param name="spanContext1">First SpanContext to compare.</param>
     /// <param name="spanContext2">Second SpanContext to compare.</param>
-    public static bool operator !=(SpanContext spanContext1, SpanContext spanContext2) => !spanContext1.Equals(spanContext2);
+    public static bool operator !=(SpanContext spanContext1, SpanContext spanContext2)
+        => !spanContext1.Equals(spanContext2);
 
     /// <inheritdoc/>
     public override int GetHashCode()
-    {
-        return this.ActivityContext.GetHashCode();
-    }
+        => this.ActivityContext.GetHashCode();
 
     /// <inheritdoc/>
-    public override bool Equals(object obj)
-    {
-        return (obj is SpanContext ctx) && this.ActivityContext.Equals(ctx.ActivityContext);
-    }
+    public override bool Equals(object? obj)
+        => obj is SpanContext ctx && this.Equals(ctx);
 
     /// <inheritdoc/>
     public bool Equals(SpanContext other)
-    {
-        return this.ActivityContext.Equals(other.ActivityContext);
-    }
+        => this.ActivityContext.Equals(other.ActivityContext);
 
     private static bool IsTraceIdValid(ActivityTraceId traceId)
-    {
-        return traceId != default;
-    }
+        => traceId != default;
 
     private static bool IsSpanIdValid(ActivitySpanId spanId)
-    {
-        return spanId != default;
-    }
+        => spanId != default;
 }
diff --git a/src/OpenTelemetry.Api/Trace/SpanKind.cs b/src/OpenTelemetry.Api/Trace/SpanKind.cs
index 12889623fa2..a8d55dcc7eb 100644
--- a/src/OpenTelemetry.Api/Trace/SpanKind.cs
+++ b/src/OpenTelemetry.Api/Trace/SpanKind.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 namespace OpenTelemetry.Trace;
 
 /// <summary>
diff --git a/src/OpenTelemetry.Api/Trace/Status.cs b/src/OpenTelemetry.Api/Trace/Status.cs
index 3904123a0e9..3eb4cb9e6b2 100644
--- a/src/OpenTelemetry.Api/Trace/Status.cs
+++ b/src/OpenTelemetry.Api/Trace/Status.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 namespace OpenTelemetry.Trace;
 
 /// <summary>
@@ -36,7 +38,7 @@ namespace OpenTelemetry.Trace;
     /// </summary>
     public static readonly Status Error = new(StatusCode.Error);
 
-    internal Status(StatusCode statusCode, string description = null)
+    internal Status(StatusCode statusCode, string? description = null)
     {
         this.StatusCode = statusCode;
         this.Description = description;
@@ -50,7 +52,7 @@ internal Status(StatusCode statusCode, string description = null)
     /// <summary>
     /// Gets the status description.
     /// </summary>
-    public string Description { get; }
+    public string? Description { get; }
 
     /// <summary>
     /// Compare two <see cref="Status"/> for equality.
@@ -78,7 +80,7 @@ internal Status(StatusCode statusCode, string description = null)
     /// </remarks>
     /// <param name="description">Description of the status.</param>
     /// <returns>New instance of the status class with the description populated.</returns>
-    public Status WithDescription(string description)
+    public Status WithDescription(string? description)
     {
         if (this.StatusCode != StatusCode.Error || this.Description == description)
         {
@@ -89,16 +91,8 @@ public Status WithDescription(string description)
     }
 
     /// <inheritdoc/>
-    public override bool Equals(object obj)
-    {
-        if (obj is not Status)
-        {
-            return false;
-        }
-
-        var that = (Status)obj;
-        return this.StatusCode == that.StatusCode && this.Description == that.Description;
-    }
+    public override bool Equals(object? obj)
+        => obj is Status status && this.Equals(status);
 
     /// <inheritdoc/>
     public override int GetHashCode()
@@ -125,7 +119,5 @@ public override string ToString()
 
     /// <inheritdoc/>
     public bool Equals(Status other)
-    {
-        return this.StatusCode == other.StatusCode && this.Description == other.Description;
-    }
+        => this.StatusCode == other.StatusCode && this.Description == other.Description;
 }
diff --git a/src/OpenTelemetry.Api/Trace/StatusCode.cs b/src/OpenTelemetry.Api/Trace/StatusCode.cs
index 339a8f043de..c749d570d93 100644
--- a/src/OpenTelemetry.Api/Trace/StatusCode.cs
+++ b/src/OpenTelemetry.Api/Trace/StatusCode.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 namespace OpenTelemetry.Trace;
 
 /// <summary>
diff --git a/src/OpenTelemetry.Api/Trace/TelemetrySpan.cs b/src/OpenTelemetry.Api/Trace/TelemetrySpan.cs
index 6b8fe4e61db..ef5b5240737 100644
--- a/src/OpenTelemetry.Api/Trace/TelemetrySpan.cs
+++ b/src/OpenTelemetry.Api/Trace/TelemetrySpan.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using OpenTelemetry.Internal;
@@ -23,13 +25,13 @@ namespace OpenTelemetry.Trace;
 /// <summary>
 /// Span represents a single operation within a trace.
 /// </summary>
-/// <remarks>TelemetrySpan is a wrapper around <see cref="Activity"/> class.</remarks>
+/// <remarks>TelemetrySpan is a wrapper around <see cref="System.Diagnostics.Activity"/> class.</remarks>
 public class TelemetrySpan : IDisposable
 {
     internal static readonly TelemetrySpan NoopInstance = new(null);
-    internal readonly Activity Activity;
+    internal readonly Activity? Activity;
 
-    internal TelemetrySpan(Activity activity)
+    internal TelemetrySpan(Activity? activity)
     {
         this.Activity = activity;
     }
@@ -38,48 +40,19 @@ internal TelemetrySpan(Activity activity)
     /// Gets the span context.
     /// </summary>
     public SpanContext Context
-    {
-        get
-        {
-            if (this.Activity == null)
-            {
-                return default;
-            }
-            else
-            {
-                return new SpanContext(this.Activity.Context);
-            }
-        }
-    }
+        => this.Activity == null ? default : new SpanContext(this.Activity.Context);
 
     /// <summary>
     /// Gets a value indicating whether this span will be recorded.
     /// </summary>
     public bool IsRecording
-    {
-        get
-        {
-            return this.Activity != null && this.Activity.IsAllDataRequested;
-        }
-    }
+        => this.Activity?.IsAllDataRequested == true;
 
     /// <summary>
     /// Gets the identity of the parent span id, if any.
     /// </summary>
     public ActivitySpanId ParentSpanId
-    {
-        get
-        {
-            if (this.Activity == null)
-            {
-                return default;
-            }
-            else
-            {
-                return this.Activity.ParentSpanId;
-            }
-        }
-    }
+        => this.Activity?.ParentSpanId ?? default;
 
     /// <summary>
     /// Sets the status of the span execution.
@@ -117,7 +90,7 @@ public TelemetrySpan UpdateName(string name)
     /// <param name="value">Attribute value.</param>
     /// <returns>The <see cref="TelemetrySpan"/> instance for chaining.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public TelemetrySpan SetAttribute(string key, string value)
+    public TelemetrySpan SetAttribute(string key, string? value)
     {
         this.SetAttributeInternal(key, value);
         return this;
@@ -169,7 +142,7 @@ public TelemetrySpan SetAttribute(string key, double value)
     /// <param name="values">Attribute values.</param>
     /// <returns>The <see cref="TelemetrySpan"/> instance for chaining.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public TelemetrySpan SetAttribute(string key, string[] values)
+    public TelemetrySpan SetAttribute(string key, string?[]? values)
     {
         this.SetAttributeInternal(key, values);
         return this;
@@ -182,7 +155,7 @@ public TelemetrySpan SetAttribute(string key, string[] values)
     /// <param name="values">Attribute values.</param>
     /// <returns>The <see cref="TelemetrySpan"/> instance for chaining.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public TelemetrySpan SetAttribute(string key, int[] values)
+    public TelemetrySpan SetAttribute(string key, int[]? values)
     {
         this.SetAttributeInternal(key, values);
         return this;
@@ -195,7 +168,7 @@ public TelemetrySpan SetAttribute(string key, int[] values)
     /// <param name="values">Attribute values.</param>
     /// <returns>The <see cref="TelemetrySpan"/> instance for chaining.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public TelemetrySpan SetAttribute(string key, bool[] values)
+    public TelemetrySpan SetAttribute(string key, bool[]? values)
     {
         this.SetAttributeInternal(key, values);
         return this;
@@ -208,7 +181,7 @@ public TelemetrySpan SetAttribute(string key, bool[] values)
     /// <param name="values">Attribute values.</param>
     /// <returns>The <see cref="TelemetrySpan"/> instance for chaining.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public TelemetrySpan SetAttribute(string key, double[] values)
+    public TelemetrySpan SetAttribute(string key, double[]? values)
     {
         this.SetAttributeInternal(key, values);
         return this;
@@ -246,7 +219,7 @@ public TelemetrySpan AddEvent(string name, DateTimeOffset timestamp)
     /// <param name="attributes">Attributes for the event.</param>
     /// <returns>The <see cref="TelemetrySpan"/> instance for chaining.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public TelemetrySpan AddEvent(string name, SpanAttributes attributes)
+    public TelemetrySpan AddEvent(string name, SpanAttributes? attributes)
     {
         this.AddEventInternal(name, default, attributes?.Attributes);
         return this;
@@ -260,7 +233,7 @@ public TelemetrySpan AddEvent(string name, SpanAttributes attributes)
     /// <param name="attributes">Attributes for the event.</param>
     /// <returns>The <see cref="TelemetrySpan"/> instance for chaining.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public TelemetrySpan AddEvent(string name, DateTimeOffset timestamp, SpanAttributes attributes)
+    public TelemetrySpan AddEvent(string name, DateTimeOffset timestamp, SpanAttributes? attributes)
     {
         this.AddEventInternal(name, timestamp, attributes?.Attributes);
         return this;
@@ -282,8 +255,12 @@ public void End()
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void End(DateTimeOffset endTimestamp)
     {
-        this.Activity?.SetEndTime(endTimestamp.UtcDateTime);
-        this.Activity?.Stop();
+        var activity = this.Activity;
+        if (activity != null)
+        {
+            activity.SetEndTime(endTimestamp.UtcDateTime);
+            activity.Stop();
+        }
     }
 
     /// <summary>
@@ -292,7 +269,7 @@ public void End(DateTimeOffset endTimestamp)
     /// <param name="ex">Exception to be recorded.</param>
     /// <returns>The <see cref="TelemetrySpan"/> instance for chaining.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public TelemetrySpan RecordException(Exception ex)
+    public TelemetrySpan RecordException(Exception? ex)
     {
         if (ex == null)
         {
@@ -309,9 +286,10 @@ public TelemetrySpan RecordException(Exception ex)
     /// <param name="message">Message of the exception to be recorded.</param>
     /// <param name="stacktrace">Stacktrace of the exception to be recorded.</param>
     /// <returns>The <see cref="TelemetrySpan"/> instance for chaining.</returns>
-    public TelemetrySpan RecordException(string type, string message, string stacktrace)
+    public TelemetrySpan RecordException(string? type, string? message, string? stacktrace)
     {
         SpanAttributes attributes = new SpanAttributes();
+
         if (!string.IsNullOrWhiteSpace(type))
         {
             attributes.Add(SemanticConventions.AttributeExceptionType, type);
@@ -348,9 +326,7 @@ public void Dispose()
     /// </summary>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     internal void Activate()
-    {
-        Activity.Current = this.Activity;
-    }
+        => Activity.Current = this.Activity;
 
     /// <summary>
     /// Releases the unmanaged resources used by this class and optionally releases the managed resources.
@@ -358,22 +334,25 @@ internal void Activate()
     /// <param name="disposing"><see langword="true"/> to release both managed and unmanaged resources; <see langword="false"/> to release only unmanaged resources.</param>
     protected virtual void Dispose(bool disposing)
     {
-        this.Activity?.Dispose();
+        if (disposing)
+        {
+            this.Activity?.Dispose();
+        }
     }
 
-    private void SetAttributeInternal(string key, object value)
+    private void SetAttributeInternal(string key, object? value)
     {
         if (this.IsRecording)
         {
-            this.Activity.SetTag(key, value);
+            this.Activity!.SetTag(key, value);
         }
     }
 
-    private void AddEventInternal(string name, DateTimeOffset timestamp = default, ActivityTagsCollection tags = null)
+    private void AddEventInternal(string name, DateTimeOffset timestamp = default, ActivityTagsCollection? tags = null)
     {
         if (this.IsRecording)
         {
-            this.Activity.AddEvent(new ActivityEvent(name, timestamp, tags));
+            this.Activity!.AddEvent(new ActivityEvent(name, timestamp, tags));
         }
     }
 }
diff --git a/src/OpenTelemetry.Api/Trace/Tracer.cs b/src/OpenTelemetry.Api/Trace/Tracer.cs
index 62c430c3bce..a7a0e2ba34e 100644
--- a/src/OpenTelemetry.Api/Trace/Tracer.cs
+++ b/src/OpenTelemetry.Api/Trace/Tracer.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
@@ -23,7 +25,7 @@ namespace OpenTelemetry.Trace;
 /// <summary>
 /// Tracer is the class responsible for creating <see cref="TelemetrySpan"/>.
 /// </summary>
-/// <remarks>Tracer is a wrapper around <see cref="ActivitySource"/> class.</remarks>
+/// <remarks>Tracer is a wrapper around <see cref="System.Diagnostics.ActivitySource"/> class.</remarks>
 public class Tracer
 {
     internal readonly ActivitySource ActivitySource;
@@ -53,12 +55,15 @@ public static TelemetrySpan CurrentSpan
     }
 
     /// <summary>
-    /// Makes the given span as the current one.
+    /// Sets the given span as the current one in the context.
     /// </summary>
     /// <param name="span">The span to be made current.</param>
-    /// <returns>The current span.</returns>
+    /// <returns>The supplied span for call chaining.</returns>
+#if NET6_0_OR_GREATER
+    [return: NotNullIfNotNull(nameof(span))]
+#endif
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static TelemetrySpan WithSpan(TelemetrySpan span)
+    public static TelemetrySpan? WithSpan(TelemetrySpan? span)
     {
         span?.Activate();
         return span;
@@ -74,7 +79,12 @@ public static TelemetrySpan WithSpan(TelemetrySpan span)
     /// <param name="startTime"> Start time for the span.</param>
     /// <returns>Span instance.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public TelemetrySpan StartRootSpan(string name, SpanKind kind = SpanKind.Internal, SpanAttributes initialAttributes = null, IEnumerable<Link> links = null, DateTimeOffset startTime = default)
+    public TelemetrySpan StartRootSpan(
+        string name,
+        SpanKind kind = SpanKind.Internal,
+        SpanAttributes? initialAttributes = null,
+        IEnumerable<Link>? links = null,
+        DateTimeOffset startTime = default)
     {
         return this.StartSpanHelper(false, name, kind, default, initialAttributes, links, startTime);
     }
@@ -91,7 +101,13 @@ public TelemetrySpan StartRootSpan(string name, SpanKind kind = SpanKind.Interna
     /// <returns>Span instance.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     [SuppressMessage("roslyn", "RS0026", Justification = "TODO: fix APIs that violate the backcompt requirement - multiple overloads with optional parameters: https://github.com/dotnet/roslyn/blob/main/docs/Adding%20Optional%20Parameters%20in%20Public%20API.md.")]
-    public TelemetrySpan StartSpan(string name, SpanKind kind, in TelemetrySpan parentSpan, SpanAttributes initialAttributes = null, IEnumerable<Link> links = null, DateTimeOffset startTime = default)
+    public TelemetrySpan StartSpan(
+        string name,
+        SpanKind kind,
+        in TelemetrySpan? parentSpan, // <- TODO: Clean this up if we ever do a major release w/ breaking changes. The "in" here was probably a copy/paste mistake. Removing would be source compatible but binary breaking.
+        SpanAttributes? initialAttributes = null,
+        IEnumerable<Link>? links = null,
+        DateTimeOffset startTime = default)
     {
         return this.StartSpan(name, kind, parentSpan?.Context ?? default, initialAttributes, links, startTime);
     }
@@ -108,9 +124,15 @@ public TelemetrySpan StartSpan(string name, SpanKind kind, in TelemetrySpan pare
     /// <returns>Span instance.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     [SuppressMessage("roslyn", "RS0026", Justification = "TODO: fix APIs that violate the backcompt requirement - multiple overloads with optional parameters: https://github.com/dotnet/roslyn/blob/main/docs/Adding%20Optional%20Parameters%20in%20Public%20API.md.")]
-    public TelemetrySpan StartSpan(string name, SpanKind kind = SpanKind.Internal, in SpanContext parentContext = default, SpanAttributes initialAttributes = null, IEnumerable<Link> links = null, DateTimeOffset startTime = default)
+    public TelemetrySpan StartSpan(
+        string name,
+        SpanKind kind = SpanKind.Internal,
+        in SpanContext parentContext = default,
+        SpanAttributes? initialAttributes = null,
+        IEnumerable<Link>? links = null,
+        DateTimeOffset startTime = default)
     {
-        return this.StartSpanHelper(false, name, kind, parentContext, initialAttributes, links, startTime);
+        return this.StartSpanHelper(false, name, kind, in parentContext, initialAttributes, links, startTime);
     }
 
     /// <summary>
@@ -125,7 +147,13 @@ public TelemetrySpan StartSpan(string name, SpanKind kind = SpanKind.Internal, i
     /// <returns>Span instance.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     [SuppressMessage("roslyn", "RS0026", Justification = "TODO: fix APIs that violate the backcompt requirement - multiple overloads with optional parameters: https://github.com/dotnet/roslyn/blob/main/docs/Adding%20Optional%20Parameters%20in%20Public%20API.md.")]
-    public TelemetrySpan StartActiveSpan(string name, SpanKind kind, in TelemetrySpan parentSpan, SpanAttributes initialAttributes = null, IEnumerable<Link> links = null, DateTimeOffset startTime = default)
+    public TelemetrySpan StartActiveSpan(
+        string name,
+        SpanKind kind,
+        in TelemetrySpan? parentSpan, // <- TODO: Clean this up if we ever do a major release w/ breaking changes. The "in" here was probably a copy/paste mistake. Removing would be source compatible but binary breaking.
+        SpanAttributes? initialAttributes = null,
+        IEnumerable<Link>? links = null,
+        DateTimeOffset startTime = default)
     {
         return this.StartActiveSpan(name, kind, parentSpan?.Context ?? default, initialAttributes, links, startTime);
     }
@@ -142,9 +170,15 @@ public TelemetrySpan StartActiveSpan(string name, SpanKind kind, in TelemetrySpa
     /// <returns>Span instance.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     [SuppressMessage("roslyn", "RS0026", Justification = "TODO: fix APIs that violate the backcompt requirement - multiple overloads with optional parameters: https://github.com/dotnet/roslyn/blob/main/docs/Adding%20Optional%20Parameters%20in%20Public%20API.md.")]
-    public TelemetrySpan StartActiveSpan(string name, SpanKind kind = SpanKind.Internal, in SpanContext parentContext = default, SpanAttributes initialAttributes = null, IEnumerable<Link> links = null, DateTimeOffset startTime = default)
+    public TelemetrySpan StartActiveSpan(
+        string name,
+        SpanKind kind = SpanKind.Internal,
+        in SpanContext parentContext = default,
+        SpanAttributes? initialAttributes = null,
+        IEnumerable<Link>? links = null,
+        DateTimeOffset startTime = default)
     {
-        return this.StartSpanHelper(true, name, kind, parentContext, initialAttributes, links, startTime);
+        return this.StartSpanHelper(true, name, kind, in parentContext, initialAttributes, links, startTime);
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -162,7 +196,14 @@ private static ActivityKind ConvertToActivityKind(SpanKind kind)
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private TelemetrySpan StartSpanHelper(bool isActiveSpan, string name, SpanKind kind, in SpanContext parentContext = default, SpanAttributes initialAttributes = null, IEnumerable<Link> links = null, DateTimeOffset startTime = default)
+    private TelemetrySpan StartSpanHelper(
+        bool isActiveSpan,
+        string name,
+        SpanKind kind,
+        in SpanContext parentContext = default,
+        SpanAttributes? initialAttributes = null,
+        IEnumerable<Link>? links = null,
+        DateTimeOffset startTime = default)
     {
         if (!this.ActivitySource.HasListeners())
         {
@@ -171,12 +212,7 @@ private TelemetrySpan StartSpanHelper(bool isActiveSpan, string name, SpanKind k
 
         var activityKind = ConvertToActivityKind(kind);
         var activityLinks = links?.Select(l => l.ActivityLink);
-
-        Activity previousActivity = null;
-        if (!isActiveSpan)
-        {
-            previousActivity = Activity.Current;
-        }
+        var previousActivity = !isActiveSpan ? Activity.Current : null;
 
         var activity = this.ActivitySource.StartActivity(name, activityKind, parentContext.ActivityContext, initialAttributes?.Attributes ?? null, activityLinks, startTime);
         if (activity == null)
diff --git a/src/OpenTelemetry.Api/Trace/TracerProvider.cs b/src/OpenTelemetry.Api/Trace/TracerProvider.cs
index ba60970d7ec..c7611bff428 100644
--- a/src/OpenTelemetry.Api/Trace/TracerProvider.cs
+++ b/src/OpenTelemetry.Api/Trace/TracerProvider.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 using System.Diagnostics;
 
 namespace OpenTelemetry.Trace;
@@ -41,13 +43,6 @@ protected TracerProvider()
     /// <param name="name">Name identifying the instrumentation library.</param>
     /// <param name="version">Version of the instrumentation library.</param>
     /// <returns>Tracer instance.</returns>
-    public Tracer GetTracer(string name, string version = null)
-    {
-        if (name == null)
-        {
-            name = string.Empty;
-        }
-
-        return new Tracer(new ActivitySource(name, version));
-    }
+    public Tracer GetTracer(string name, string? version = null)
+        => new(new ActivitySource(name ?? string.Empty, version));
 }
diff --git a/src/OpenTelemetry.Api/Trace/TracerProviderBuilder.cs b/src/OpenTelemetry.Api/Trace/TracerProviderBuilder.cs
index 1f57c20f4b1..1b1058ef81f 100644
--- a/src/OpenTelemetry.Api/Trace/TracerProviderBuilder.cs
+++ b/src/OpenTelemetry.Api/Trace/TracerProviderBuilder.cs
@@ -13,6 +13,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 // </copyright>
+
+#nullable enable
+
 using System.Diagnostics;
 
 namespace OpenTelemetry.Trace;
@@ -37,10 +40,10 @@ protected TracerProviderBuilder()
     /// <returns>Returns <see cref="TracerProviderBuilder"/> for chaining.</returns>
     public abstract TracerProviderBuilder AddInstrumentation<TInstrumentation>(
         Func<TInstrumentation> instrumentationFactory)
-        where TInstrumentation : class;
+        where TInstrumentation : class?;
 
     /// <summary>
-    /// Adds given activitysource names to the list of subscribed sources.
+    /// Adds the given <see cref="ActivitySource"/> names to the list of subscribed sources.
     /// </summary>
     /// <param name="names">Activity source names.</param>
     /// <returns>Returns <see cref="TracerProviderBuilder"/> for chaining.</returns>
diff --git a/src/OpenTelemetry/.publicApi/Stable/net462/PublicAPI.Shipped.txt b/src/OpenTelemetry/.publicApi/Stable/net462/PublicAPI.Shipped.txt
index 210314bea9b..96178a813ed 100644
--- a/src/OpenTelemetry/.publicApi/Stable/net462/PublicAPI.Shipped.txt
+++ b/src/OpenTelemetry/.publicApi/Stable/net462/PublicAPI.Shipped.txt
@@ -17,8 +17,8 @@ OpenTelemetry.Metrics.MetricStreamConfiguration.Name.set -> void
 OpenTelemetry.Metrics.MetricStreamConfiguration.TagKeys.get -> string![]?
 OpenTelemetry.Metrics.MetricStreamConfiguration.TagKeys.set -> void
 OpenTelemetry.Metrics.PeriodicExportingMetricReader.PeriodicExportingMetricReader(OpenTelemetry.BaseExporter<OpenTelemetry.Metrics.Metric!>! exporter, int exportIntervalMilliseconds = 60000, int exportTimeoutMilliseconds = 30000) -> void
-~override OpenTelemetry.Metrics.MeterProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
-~override OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+override OpenTelemetry.Metrics.MeterProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+override OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
 readonly OpenTelemetry.Metrics.BaseExportingMetricReader.exporter -> OpenTelemetry.BaseExporter<OpenTelemetry.Metrics.Metric!>!
 static OpenTelemetry.Metrics.MeterProviderExtensions.ForceFlush(this OpenTelemetry.Metrics.MeterProvider! provider, int timeoutMilliseconds = -1) -> bool
 static OpenTelemetry.Metrics.MeterProviderExtensions.Shutdown(this OpenTelemetry.Metrics.MeterProvider! provider, int timeoutMilliseconds = -1) -> bool
@@ -319,7 +319,7 @@ OpenTelemetry.Trace.SamplingResult.TraceStateString.get -> string?
 OpenTelemetry.Trace.TraceIdRatioBasedSampler
 OpenTelemetry.Trace.TraceIdRatioBasedSampler.TraceIdRatioBasedSampler(double probability) -> void
 OpenTelemetry.Trace.TracerProviderBuilderBase
-OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation(string! instrumentationName, string! instrumentationVersion, System.Func<object!>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation(string! instrumentationName, string! instrumentationVersion, System.Func<object?>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
 OpenTelemetry.Trace.TracerProviderBuilderBase.Build() -> OpenTelemetry.Trace.TracerProvider!
 OpenTelemetry.Trace.TracerProviderBuilderBase.TracerProviderBuilderBase() -> void
 OpenTelemetry.Trace.TracerProviderBuilderExtensions
diff --git a/src/OpenTelemetry/.publicApi/Stable/net6.0/PublicAPI.Shipped.txt b/src/OpenTelemetry/.publicApi/Stable/net6.0/PublicAPI.Shipped.txt
index 210314bea9b..96178a813ed 100644
--- a/src/OpenTelemetry/.publicApi/Stable/net6.0/PublicAPI.Shipped.txt
+++ b/src/OpenTelemetry/.publicApi/Stable/net6.0/PublicAPI.Shipped.txt
@@ -17,8 +17,8 @@ OpenTelemetry.Metrics.MetricStreamConfiguration.Name.set -> void
 OpenTelemetry.Metrics.MetricStreamConfiguration.TagKeys.get -> string![]?
 OpenTelemetry.Metrics.MetricStreamConfiguration.TagKeys.set -> void
 OpenTelemetry.Metrics.PeriodicExportingMetricReader.PeriodicExportingMetricReader(OpenTelemetry.BaseExporter<OpenTelemetry.Metrics.Metric!>! exporter, int exportIntervalMilliseconds = 60000, int exportTimeoutMilliseconds = 30000) -> void
-~override OpenTelemetry.Metrics.MeterProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
-~override OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+override OpenTelemetry.Metrics.MeterProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+override OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
 readonly OpenTelemetry.Metrics.BaseExportingMetricReader.exporter -> OpenTelemetry.BaseExporter<OpenTelemetry.Metrics.Metric!>!
 static OpenTelemetry.Metrics.MeterProviderExtensions.ForceFlush(this OpenTelemetry.Metrics.MeterProvider! provider, int timeoutMilliseconds = -1) -> bool
 static OpenTelemetry.Metrics.MeterProviderExtensions.Shutdown(this OpenTelemetry.Metrics.MeterProvider! provider, int timeoutMilliseconds = -1) -> bool
@@ -319,7 +319,7 @@ OpenTelemetry.Trace.SamplingResult.TraceStateString.get -> string?
 OpenTelemetry.Trace.TraceIdRatioBasedSampler
 OpenTelemetry.Trace.TraceIdRatioBasedSampler.TraceIdRatioBasedSampler(double probability) -> void
 OpenTelemetry.Trace.TracerProviderBuilderBase
-OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation(string! instrumentationName, string! instrumentationVersion, System.Func<object!>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation(string! instrumentationName, string! instrumentationVersion, System.Func<object?>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
 OpenTelemetry.Trace.TracerProviderBuilderBase.Build() -> OpenTelemetry.Trace.TracerProvider!
 OpenTelemetry.Trace.TracerProviderBuilderBase.TracerProviderBuilderBase() -> void
 OpenTelemetry.Trace.TracerProviderBuilderExtensions
diff --git a/src/OpenTelemetry/.publicApi/Stable/netstandard2.0/PublicAPI.Shipped.txt b/src/OpenTelemetry/.publicApi/Stable/netstandard2.0/PublicAPI.Shipped.txt
index 210314bea9b..96178a813ed 100644
--- a/src/OpenTelemetry/.publicApi/Stable/netstandard2.0/PublicAPI.Shipped.txt
+++ b/src/OpenTelemetry/.publicApi/Stable/netstandard2.0/PublicAPI.Shipped.txt
@@ -17,8 +17,8 @@ OpenTelemetry.Metrics.MetricStreamConfiguration.Name.set -> void
 OpenTelemetry.Metrics.MetricStreamConfiguration.TagKeys.get -> string![]?
 OpenTelemetry.Metrics.MetricStreamConfiguration.TagKeys.set -> void
 OpenTelemetry.Metrics.PeriodicExportingMetricReader.PeriodicExportingMetricReader(OpenTelemetry.BaseExporter<OpenTelemetry.Metrics.Metric!>! exporter, int exportIntervalMilliseconds = 60000, int exportTimeoutMilliseconds = 30000) -> void
-~override OpenTelemetry.Metrics.MeterProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
-~override OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+override OpenTelemetry.Metrics.MeterProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+override OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
 readonly OpenTelemetry.Metrics.BaseExportingMetricReader.exporter -> OpenTelemetry.BaseExporter<OpenTelemetry.Metrics.Metric!>!
 static OpenTelemetry.Metrics.MeterProviderExtensions.ForceFlush(this OpenTelemetry.Metrics.MeterProvider! provider, int timeoutMilliseconds = -1) -> bool
 static OpenTelemetry.Metrics.MeterProviderExtensions.Shutdown(this OpenTelemetry.Metrics.MeterProvider! provider, int timeoutMilliseconds = -1) -> bool
@@ -319,7 +319,7 @@ OpenTelemetry.Trace.SamplingResult.TraceStateString.get -> string?
 OpenTelemetry.Trace.TraceIdRatioBasedSampler
 OpenTelemetry.Trace.TraceIdRatioBasedSampler.TraceIdRatioBasedSampler(double probability) -> void
 OpenTelemetry.Trace.TracerProviderBuilderBase
-OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation(string! instrumentationName, string! instrumentationVersion, System.Func<object!>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation(string! instrumentationName, string! instrumentationVersion, System.Func<object?>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
 OpenTelemetry.Trace.TracerProviderBuilderBase.Build() -> OpenTelemetry.Trace.TracerProvider!
 OpenTelemetry.Trace.TracerProviderBuilderBase.TracerProviderBuilderBase() -> void
 OpenTelemetry.Trace.TracerProviderBuilderExtensions
diff --git a/src/OpenTelemetry/.publicApi/Stable/netstandard2.1/PublicAPI.Shipped.txt b/src/OpenTelemetry/.publicApi/Stable/netstandard2.1/PublicAPI.Shipped.txt
index 210314bea9b..96178a813ed 100644
--- a/src/OpenTelemetry/.publicApi/Stable/netstandard2.1/PublicAPI.Shipped.txt
+++ b/src/OpenTelemetry/.publicApi/Stable/netstandard2.1/PublicAPI.Shipped.txt
@@ -17,8 +17,8 @@ OpenTelemetry.Metrics.MetricStreamConfiguration.Name.set -> void
 OpenTelemetry.Metrics.MetricStreamConfiguration.TagKeys.get -> string![]?
 OpenTelemetry.Metrics.MetricStreamConfiguration.TagKeys.set -> void
 OpenTelemetry.Metrics.PeriodicExportingMetricReader.PeriodicExportingMetricReader(OpenTelemetry.BaseExporter<OpenTelemetry.Metrics.Metric!>! exporter, int exportIntervalMilliseconds = 60000, int exportTimeoutMilliseconds = 30000) -> void
-~override OpenTelemetry.Metrics.MeterProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
-~override OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+override OpenTelemetry.Metrics.MeterProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+override OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
 readonly OpenTelemetry.Metrics.BaseExportingMetricReader.exporter -> OpenTelemetry.BaseExporter<OpenTelemetry.Metrics.Metric!>!
 static OpenTelemetry.Metrics.MeterProviderExtensions.ForceFlush(this OpenTelemetry.Metrics.MeterProvider! provider, int timeoutMilliseconds = -1) -> bool
 static OpenTelemetry.Metrics.MeterProviderExtensions.Shutdown(this OpenTelemetry.Metrics.MeterProvider! provider, int timeoutMilliseconds = -1) -> bool
@@ -319,7 +319,7 @@ OpenTelemetry.Trace.SamplingResult.TraceStateString.get -> string?
 OpenTelemetry.Trace.TraceIdRatioBasedSampler
 OpenTelemetry.Trace.TraceIdRatioBasedSampler.TraceIdRatioBasedSampler(double probability) -> void
 OpenTelemetry.Trace.TracerProviderBuilderBase
-OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation(string! instrumentationName, string! instrumentationVersion, System.Func<object!>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
+OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation(string! instrumentationName, string! instrumentationVersion, System.Func<object?>! instrumentationFactory) -> OpenTelemetry.Trace.TracerProviderBuilder!
 OpenTelemetry.Trace.TracerProviderBuilderBase.Build() -> OpenTelemetry.Trace.TracerProvider!
 OpenTelemetry.Trace.TracerProviderBuilderBase.TracerProviderBuilderBase() -> void
 OpenTelemetry.Trace.TracerProviderBuilderExtensions
diff --git a/src/OpenTelemetry/ApiCompatBaseline.txt b/src/OpenTelemetry/ApiCompatBaseline.txt
new file mode 100644
index 00000000000..f6962355594
--- /dev/null
+++ b/src/OpenTelemetry/ApiCompatBaseline.txt
@@ -0,0 +1,4 @@
+Compat issues with assembly OpenTelemetry:
+CannotChangeAttribute : Attribute 'System.Runtime.CompilerServices.NullableAttribute' on generic param 'TInstrumentation' on member 'OpenTelemetry.Metrics.MeterProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>)' changed from '[NullableAttribute((byte)0)]' in the contract to '[NullableAttribute((byte)2)]' in the implementation.
+CannotChangeAttribute : Attribute 'System.Runtime.CompilerServices.NullableAttribute' on generic param 'TInstrumentation' on member 'OpenTelemetry.Trace.TracerProviderBuilderBase.AddInstrumentation<TInstrumentation>(System.Func<TInstrumentation>)' changed from '[NullableAttribute((byte)0)]' in the contract to '[NullableAttribute((byte)2)]' in the implementation.
+Total Issues: 2
diff --git a/src/OpenTelemetry/CHANGELOG.md b/src/OpenTelemetry/CHANGELOG.md
index eb91c8b79ec..78891b4e3a2 100644
--- a/src/OpenTelemetry/CHANGELOG.md
+++ b/src/OpenTelemetry/CHANGELOG.md
@@ -4,17 +4,22 @@
 
 * Update `AggregatorStore` to reclaim unused MetricPoints for Delta aggregation
   temporality.
-  ([#4486](https://github.com/open-telemetry/opentelemetry-dotnet/issues/4486))
+  ([#4486](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4486))
+
+* Fixed a bug where `TracerProviderBuilderBase` was not invoking the
+  `instrumentationFactory` delegate passed to the `protected`
+  `AddInstrumentation` method.
+  ([#4873](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4873))
 
 ## 1.6.0
 
 Released 2023-Sep-05
 
 * Increased the character limit of the Meter instrument name from 63 to 255.
-  ([#4774](https://github.com/open-telemetry/opentelemetry-dotnet/issues/4774))
+  ([#4798](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4798))
 
 * Update default size for `SimpleExemplarReservoir` to `1`.
-  ([#4803](https://github.com/open-telemetry/opentelemetry-dotnet/issues/4803))
+  ([#4803](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4803))
 
 * Update Metrics SDK to override the default histogram buckets for a set of
   well-known histogram metrics from ASP.NET Core and HttpClient runtime. These
diff --git a/src/OpenTelemetry/Logs/Builder/LoggerProviderBuilderSdk.cs b/src/OpenTelemetry/Logs/Builder/LoggerProviderBuilderSdk.cs
index 2de58eccb59..626a744fea3 100644
--- a/src/OpenTelemetry/Logs/Builder/LoggerProviderBuilderSdk.cs
+++ b/src/OpenTelemetry/Logs/Builder/LoggerProviderBuilderSdk.cs
@@ -55,8 +55,7 @@ public void RegisterProvider(LoggerProviderSdk loggerProvider)
         this.loggerProvider = loggerProvider;
     }
 
-    public override LoggerProviderBuilder AddInstrumentation<TInstrumentation>(
-        Func<TInstrumentation> instrumentationFactory)
+    public override LoggerProviderBuilder AddInstrumentation<TInstrumentation>(Func<TInstrumentation> instrumentationFactory)
     {
         Debug.Assert(instrumentationFactory != null, "instrumentationFactory was null");
 
@@ -64,7 +63,7 @@ public override LoggerProviderBuilder AddInstrumentation<TInstrumentation>(
             new InstrumentationRegistration(
                 typeof(TInstrumentation).Name,
                 typeof(TInstrumentation).Assembly.GetName().Version?.ToString() ?? DefaultInstrumentationVersion,
-                instrumentationFactory!()!));
+                instrumentationFactory!()));
 
         return this;
     }
@@ -119,9 +118,9 @@ internal readonly struct InstrumentationRegistration
     {
         public readonly string Name;
         public readonly string Version;
-        public readonly object Instance;
+        public readonly object? Instance;
 
-        internal InstrumentationRegistration(string name, string version, object instance)
+        internal InstrumentationRegistration(string name, string version, object? instance)
         {
             this.Name = name;
             this.Version = version;
diff --git a/src/OpenTelemetry/Logs/LoggerProviderSdk.cs b/src/OpenTelemetry/Logs/LoggerProviderSdk.cs
index a4440d1e8e0..6d4ae3ce946 100644
--- a/src/OpenTelemetry/Logs/LoggerProviderSdk.cs
+++ b/src/OpenTelemetry/Logs/LoggerProviderSdk.cs
@@ -76,7 +76,11 @@ public LoggerProviderSdk(
 
         foreach (var instrumentation in state.Instrumentation)
         {
-            this.instrumentations.Add(instrumentation.Instance);
+            if (instrumentation.Instance is not null)
+            {
+                this.instrumentations.Add(instrumentation.Instance);
+            }
+
             instrumentationFactoriesAdded.Append(instrumentation.Name);
             instrumentationFactoriesAdded.Append(';');
         }
diff --git a/src/OpenTelemetry/Metrics/Builder/MeterProviderBuilderSdk.cs b/src/OpenTelemetry/Metrics/Builder/MeterProviderBuilderSdk.cs
index ea94ef6579a..bcca0a16456 100644
--- a/src/OpenTelemetry/Metrics/Builder/MeterProviderBuilderSdk.cs
+++ b/src/OpenTelemetry/Metrics/Builder/MeterProviderBuilderSdk.cs
@@ -111,8 +111,7 @@ public void RegisterProvider(MeterProviderSdk meterProvider)
         this.meterProvider = meterProvider;
     }
 
-    public override MeterProviderBuilder AddInstrumentation<TInstrumentation>(
-        Func<TInstrumentation> instrumentationFactory)
+    public override MeterProviderBuilder AddInstrumentation<TInstrumentation>(Func<TInstrumentation> instrumentationFactory)
     {
         Debug.Assert(instrumentationFactory != null, "instrumentationFactory was null");
 
@@ -125,17 +124,16 @@ public override MeterProviderBuilder AddInstrumentation<TInstrumentation>(
     public MeterProviderBuilder AddInstrumentation(
         string instrumentationName,
         string instrumentationVersion,
-        object instrumentation)
+        object? instrumentation)
     {
         Debug.Assert(!string.IsNullOrWhiteSpace(instrumentationName), "instrumentationName was null or whitespace");
         Debug.Assert(!string.IsNullOrWhiteSpace(instrumentationVersion), "instrumentationVersion was null or whitespace");
-        Debug.Assert(instrumentation != null, "instrumentation was null");
 
         this.Instrumentation.Add(
             new InstrumentationRegistration(
                 instrumentationName,
                 instrumentationVersion,
-                instrumentation!));
+                instrumentation));
 
         return this;
     }
@@ -236,9 +234,9 @@ internal readonly struct InstrumentationRegistration
     {
         public readonly string Name;
         public readonly string Version;
-        public readonly object Instance;
+        public readonly object? Instance;
 
-        internal InstrumentationRegistration(string name, string version, object instance)
+        internal InstrumentationRegistration(string name, string version, object? instance)
         {
             this.Name = name;
             this.Version = version;
diff --git a/src/OpenTelemetry/Metrics/MeterProviderSdk.cs b/src/OpenTelemetry/Metrics/MeterProviderSdk.cs
index 78c49aa613e..917bb0b35f8 100644
--- a/src/OpenTelemetry/Metrics/MeterProviderSdk.cs
+++ b/src/OpenTelemetry/Metrics/MeterProviderSdk.cs
@@ -129,7 +129,11 @@ internal MeterProviderSdk(
         {
             foreach (var instrumentation in state.Instrumentation)
             {
-                this.instrumentations.Add(instrumentation.Instance);
+                if (instrumentation.Instance is not null)
+                {
+                    this.instrumentations.Add(instrumentation.Instance);
+                }
+
                 instrumentationFactoriesAdded.Append(instrumentation.Name);
                 instrumentationFactoriesAdded.Append(';');
             }
diff --git a/src/OpenTelemetry/Trace/Builder/TracerProviderBuilderBase.cs b/src/OpenTelemetry/Trace/Builder/TracerProviderBuilderBase.cs
index 285b299cfb5..a2dc221e644 100644
--- a/src/OpenTelemetry/Trace/Builder/TracerProviderBuilderBase.cs
+++ b/src/OpenTelemetry/Trace/Builder/TracerProviderBuilderBase.cs
@@ -115,7 +115,7 @@ internal TracerProvider InvokeBuild()
     protected TracerProviderBuilder AddInstrumentation(
         string instrumentationName,
         string instrumentationVersion,
-        Func<object> instrumentationFactory)
+        Func<object?> instrumentationFactory)
     {
         Guard.ThrowIfNullOrWhitespace(instrumentationName);
         Guard.ThrowIfNullOrWhitespace(instrumentationVersion);
@@ -128,7 +128,7 @@ protected TracerProviderBuilder AddInstrumentation(
                 tracerProviderBuilderState.AddInstrumentation(
                     instrumentationName,
                     instrumentationVersion,
-                    instrumentationFactory);
+                    instrumentationFactory());
             }
         });
 
diff --git a/src/OpenTelemetry/Trace/Builder/TracerProviderBuilderSdk.cs b/src/OpenTelemetry/Trace/Builder/TracerProviderBuilderSdk.cs
index 58b8c2b779d..384b8ae989d 100644
--- a/src/OpenTelemetry/Trace/Builder/TracerProviderBuilderSdk.cs
+++ b/src/OpenTelemetry/Trace/Builder/TracerProviderBuilderSdk.cs
@@ -64,8 +64,7 @@ public void RegisterProvider(TracerProviderSdk tracerProvider)
         this.tracerProvider = tracerProvider;
     }
 
-    public override TracerProviderBuilder AddInstrumentation<TInstrumentation>(
-        Func<TInstrumentation> instrumentationFactory)
+    public override TracerProviderBuilder AddInstrumentation<TInstrumentation>(Func<TInstrumentation> instrumentationFactory)
     {
         Debug.Assert(instrumentationFactory != null, "instrumentationFactory was null");
 
@@ -78,17 +77,16 @@ public override TracerProviderBuilder AddInstrumentation<TInstrumentation>(
     public TracerProviderBuilder AddInstrumentation(
         string instrumentationName,
         string instrumentationVersion,
-        object instrumentation)
+        object? instrumentation)
     {
         Debug.Assert(!string.IsNullOrWhiteSpace(instrumentationName), "instrumentationName was null or whitespace");
         Debug.Assert(!string.IsNullOrWhiteSpace(instrumentationVersion), "instrumentationVersion was null or whitespace");
-        Debug.Assert(instrumentation != null, "instrumentation was null");
 
         this.Instrumentation.Add(
             new InstrumentationRegistration(
                 instrumentationName,
                 instrumentationVersion,
-                instrumentation!));
+                instrumentation));
 
         return this;
     }
@@ -199,9 +197,9 @@ internal readonly struct InstrumentationRegistration
     {
         public readonly string Name;
         public readonly string Version;
-        public readonly object Instance;
+        public readonly object? Instance;
 
-        internal InstrumentationRegistration(string name, string version, object instance)
+        internal InstrumentationRegistration(string name, string version, object? instance)
         {
             this.Name = name;
             this.Version = version;
diff --git a/src/OpenTelemetry/Trace/TracerProviderSdk.cs b/src/OpenTelemetry/Trace/TracerProviderSdk.cs
index 5cfffc1d697..fd5a8b37427 100644
--- a/src/OpenTelemetry/Trace/TracerProviderSdk.cs
+++ b/src/OpenTelemetry/Trace/TracerProviderSdk.cs
@@ -96,7 +96,11 @@ internal TracerProviderSdk(
 
         foreach (var instrumentation in state.Instrumentation)
         {
-            this.instrumentations.Add(instrumentation.Instance);
+            if (instrumentation.Instance is not null)
+            {
+                this.instrumentations.Add(instrumentation.Instance);
+            }
+
             instrumentationFactoriesAdded.Append(instrumentation.Name);
             instrumentationFactoriesAdded.Append(';');
         }
diff --git a/src/Shared/ActivityHelperExtensions.cs b/src/Shared/ActivityHelperExtensions.cs
index 023895dade1..935df229194 100644
--- a/src/Shared/ActivityHelperExtensions.cs
+++ b/src/Shared/ActivityHelperExtensions.cs
@@ -14,6 +14,8 @@
 // limitations under the License.
 // </copyright>
 
+#nullable enable
+
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using OpenTelemetry.Internal;
@@ -35,7 +37,7 @@ internal static class ActivityHelperExtensions
     /// <param name="statusDescription">Status description.</param>
     /// <returns><see langword="true"/> if <see cref="Status"/> was found on the supplied Activity.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static bool TryGetStatus(this Activity activity, out StatusCode statusCode, out string statusDescription)
+    public static bool TryGetStatus(this Activity activity, out StatusCode statusCode, out string? statusDescription)
     {
         Debug.Assert(activity != null, "Activity should not be null");
 
@@ -43,7 +45,7 @@ public static bool TryGetStatus(this Activity activity, out StatusCode statusCod
         statusCode = default;
         statusDescription = null;
 
-        foreach (ref readonly var tag in activity.EnumerateTagObjects())
+        foreach (ref readonly var tag in activity!.EnumerateTagObjects())
         {
             switch (tag.Key)
             {
@@ -80,11 +82,11 @@ public static bool TryGetStatus(this Activity activity, out StatusCode statusCod
     /// <param name="tagName">Case-sensitive tag name to retrieve.</param>
     /// <returns>Tag value or null if a match was not found.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static object GetTagValue(this Activity activity, string tagName)
+    public static object? GetTagValue(this Activity activity, string? tagName)
     {
         Debug.Assert(activity != null, "Activity should not be null");
 
-        foreach (ref readonly var tag in activity.EnumerateTagObjects())
+        foreach (ref readonly var tag in activity!.EnumerateTagObjects())
         {
             if (tag.Key == tagName)
             {
@@ -103,11 +105,11 @@ public static object GetTagValue(this Activity activity, string tagName)
     /// <param name="tagValue">Tag value.</param>
     /// <returns><see langword="true"/> if the first tag of the supplied Activity matches the user provide tag name.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static bool TryCheckFirstTag(this Activity activity, string tagName, out object tagValue)
+    public static bool TryCheckFirstTag(this Activity activity, string tagName, out object? tagValue)
     {
         Debug.Assert(activity != null, "Activity should not be null");
 
-        var enumerator = activity.EnumerateTagObjects();
+        var enumerator = activity!.EnumerateTagObjects();
 
         if (enumerator.MoveNext())
         {
diff --git a/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Logs/TestLoggerProviderBuilder.cs b/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Logs/TestLoggerProviderBuilder.cs
index 61b0c411e11..fec4069a968 100644
--- a/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Logs/TestLoggerProviderBuilder.cs
+++ b/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Logs/TestLoggerProviderBuilder.cs
@@ -42,7 +42,11 @@ public override LoggerProviderBuilder AddInstrumentation<TInstrumentation>(Func<
         }
         else
         {
-            this.Instrumentation.Add(instrumentationFactory());
+            var instrumentation = instrumentationFactory();
+            if (instrumentation is not null)
+            {
+                this.Instrumentation.Add(instrumentation);
+            }
         }
 
         return this;
diff --git a/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Metrics/TestMeterProviderBuilder.cs b/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Metrics/TestMeterProviderBuilder.cs
index 362dc70e40e..d6f4249f238 100644
--- a/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Metrics/TestMeterProviderBuilder.cs
+++ b/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Metrics/TestMeterProviderBuilder.cs
@@ -44,7 +44,11 @@ public override MeterProviderBuilder AddInstrumentation<TInstrumentation>(Func<T
         }
         else
         {
-            this.Instrumentation.Add(instrumentationFactory());
+            var instrumentation = instrumentationFactory();
+            if (instrumentation is not null)
+            {
+                this.Instrumentation.Add(instrumentation);
+            }
         }
 
         return this;
diff --git a/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Trace/TestTracerProviderBuilder.cs b/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Trace/TestTracerProviderBuilder.cs
index 73c48bcd940..51c5bbd7d82 100644
--- a/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Trace/TestTracerProviderBuilder.cs
+++ b/test/OpenTelemetry.Api.ProviderBuilderExtensions.Tests/Trace/TestTracerProviderBuilder.cs
@@ -46,7 +46,11 @@ public override TracerProviderBuilder AddInstrumentation<TInstrumentation>(Func<
         }
         else
         {
-            this.Instrumentation.Add(instrumentationFactory());
+            var instrumentation = instrumentationFactory();
+            if (instrumentation is not null)
+            {
+                this.Instrumentation.Add(instrumentation);
+            }
         }
 
         return this;
diff --git a/test/OpenTelemetry.Tests/Logs/LoggerProviderBuilderExtensionsTests.cs b/test/OpenTelemetry.Tests/Logs/LoggerProviderBuilderExtensionsTests.cs
index 022f0c5bc01..3d3e276ec56 100644
--- a/test/OpenTelemetry.Tests/Logs/LoggerProviderBuilderExtensionsTests.cs
+++ b/test/OpenTelemetry.Tests/Logs/LoggerProviderBuilderExtensionsTests.cs
@@ -33,6 +33,7 @@ public void LoggerProviderBuilderAddInstrumentationTest()
             .AddInstrumentation<CustomInstrumentation>()
             .AddInstrumentation((sp, provider) => new CustomInstrumentation() { Provider = provider })
             .AddInstrumentation(new CustomInstrumentation())
+            .AddInstrumentation(() => (object?)null)
             .Build() as LoggerProviderSdk)
         {
             Assert.NotNull(provider);
diff --git a/test/OpenTelemetry.Tests/Metrics/MeterProviderBuilderExtensionsTests.cs b/test/OpenTelemetry.Tests/Metrics/MeterProviderBuilderExtensionsTests.cs
index 38beb452133..2f19e37cf85 100644
--- a/test/OpenTelemetry.Tests/Metrics/MeterProviderBuilderExtensionsTests.cs
+++ b/test/OpenTelemetry.Tests/Metrics/MeterProviderBuilderExtensionsTests.cs
@@ -91,6 +91,7 @@ public void AddInstrumentationTest()
             .AddInstrumentation<MyInstrumentation>()
             .AddInstrumentation((sp, provider) => new MyInstrumentation() { Provider = provider })
             .AddInstrumentation(new MyInstrumentation())
+            .AddInstrumentation(() => (object)null)
             .Build() as MeterProviderSdk)
         {
             Assert.NotNull(provider);
diff --git a/test/OpenTelemetry.Tests/Trace/TracerProviderBuilderBaseTests.cs b/test/OpenTelemetry.Tests/Trace/TracerProviderBuilderBaseTests.cs
new file mode 100644
index 00000000000..d895d5cb386
--- /dev/null
+++ b/test/OpenTelemetry.Tests/Trace/TracerProviderBuilderBaseTests.cs
@@ -0,0 +1,83 @@
+// <copyright file="TracerProviderBuilderBaseTests.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+#nullable enable
+
+using Xunit;
+
+namespace OpenTelemetry.Trace.Tests;
+
+public class TracerProviderBuilderBaseTests
+{
+    [Fact]
+    public void AddInstrumentationInvokesFactoryTest()
+    {
+        bool factoryInvoked = false;
+
+        var instrumentation = new TestTracerProviderBuilder();
+        instrumentation.AddInstrumentationViaProtectedMethod(() =>
+        {
+            factoryInvoked = true;
+
+            return null;
+        });
+
+        using var provider = instrumentation.Build();
+
+        Assert.True(factoryInvoked);
+    }
+
+    [Fact]
+    public void AddInstrumentationValidatesInputTest()
+    {
+        Assert.Throws<ArgumentException>(() =>
+        {
+            new TestTracerProviderBuilder().AddInstrumentationViaProtectedMethod(
+                name: null,
+                version: "1.0.0",
+                factory: () => null);
+        });
+
+        Assert.Throws<ArgumentException>(() =>
+        {
+            new TestTracerProviderBuilder().AddInstrumentationViaProtectedMethod(
+                name: "name",
+                version: null,
+                factory: () => null);
+        });
+
+        Assert.Throws<ArgumentNullException>(() =>
+        {
+            new TestTracerProviderBuilder().AddInstrumentationViaProtectedMethod(
+                name: "name",
+                version: "1.0.0",
+                factory: null);
+        });
+    }
+
+    private sealed class TestTracerProviderBuilder : TracerProviderBuilderBase
+    {
+        public void AddInstrumentationViaProtectedMethod(Func<object?> factory)
+        {
+            this.AddInstrumentation("MyName", "MyVersion", factory);
+        }
+
+        public void AddInstrumentationViaProtectedMethod(string? name, string? version, Func<object?>? factory)
+        {
+            this.AddInstrumentation(name!, version!, factory!);
+        }
+    }
+}
diff --git a/test/OpenTelemetry.Tests/Trace/TracerProviderBuilderExtensionsTest.cs b/test/OpenTelemetry.Tests/Trace/TracerProviderBuilderExtensionsTest.cs
index a5ad07e7507..6ed2fb7c821 100644
--- a/test/OpenTelemetry.Tests/Trace/TracerProviderBuilderExtensionsTest.cs
+++ b/test/OpenTelemetry.Tests/Trace/TracerProviderBuilderExtensionsTest.cs
@@ -181,6 +181,7 @@ public void AddInstrumentationTest()
             .AddInstrumentation<MyInstrumentation>()
             .AddInstrumentation((sp, provider) => new MyInstrumentation() { Provider = provider })
             .AddInstrumentation(new MyInstrumentation())
+            .AddInstrumentation(() => (object)null)
             .Build() as TracerProviderSdk)
         {
             Assert.NotNull(provider);