Resolve trimmer warnings

Author: MaggieKimani1

src/Microsoft.OpenApi/Models/OpenApiSchema.cs

@@ -846,7 +846,11 @@ where Type.Value.HasFlag(flag)
             writer.WriteOptionalCollection(OpenApiConstants.Type, list, (w, s) => w.WriteValue(s));
         }
 
+#if NET5_0_OR_GREATER
+        private static readonly Array jsonSchemaTypeValues = System.Enum.GetValues<JsonSchemaType>();
+#else
         private static readonly Array jsonSchemaTypeValues = System.Enum.GetValues(typeof(JsonSchemaType));
+#endif
 
         private void DowncastTypeArrayToV2OrV3(JsonSchemaType schemaType, IOpenApiWriter writer, OpenApiSpecVersion version)
         {

test/Microsoft.OpenApi.Trimming.Tests/Microsoft.OpenApi.Trimming.Tests.csproj

@@ -8,7 +8,7 @@
     <PublishAot>true</PublishAot>
     <TrimmerSingleWarn>false</TrimmerSingleWarn>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
-    <NoWarn>NU1903; IL3000</NoWarn>
+    <NoWarn>NU1903</NoWarn>
     <IsPackable>false</IsPackable>
   </PropertyGroup>