diff --git a/java/src/org/openqa/selenium/devtools/CdpClientGenerator.java b/java/src/org/openqa/selenium/devtools/CdpClientGenerator.java
index f38869992733a..1d34dd66a2816 100644
--- a/java/src/org/openqa/selenium/devtools/CdpClientGenerator.java
+++ b/java/src/org/openqa/selenium/devtools/CdpClientGenerator.java
@@ -17,6 +17,7 @@
 
 package org.openqa.selenium.devtools;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.nio.file.FileVisitResult.CONTINUE;
 import static java.util.Collections.unmodifiableMap;
 import static java.util.stream.Collectors.joining;
@@ -176,8 +177,11 @@ public void parse(T target, Map<String, Object> json) {
   }
 
   private static class BaseSpec {
+    // it seems `name` is always filled from JSON
+    @SuppressWarnings({"NotNullFieldNotInitialized", "InstanceVariableMayNotBeInitialized"})
     protected String name;
-    protected String description;
+
+    protected @Nullable String description;
     protected boolean experimental;
     protected boolean deprecated;
   }
@@ -343,7 +347,7 @@ private void dumpMainClass(Path target) {
       ensureFileDoesNotExists(commandFile);
 
       try {
-        Files.write(commandFile, unit.toString().getBytes());
+        Files.write(commandFile, unit.toString().getBytes(UTF_8));
       } catch (IOException e) {
         throw new UncheckedIOException(e);
       }
@@ -426,7 +430,7 @@ public void dumpTo(Path target) {
         ensureFileDoesNotExists(eventFile);
 
         try {
-          Files.write(eventFile, unit.toString().getBytes());
+          Files.write(eventFile, unit.toString().getBytes(UTF_8));
         } catch (IOException e) {
           throw new UncheckedIOException(e);
         }
@@ -540,7 +544,7 @@ public void dumpTo(Path target) {
       ensureFileDoesNotExists(typeFile);
 
       try {
-        Files.write(typeFile, unit.toString().getBytes());
+        Files.write(typeFile, unit.toString().getBytes(UTF_8));
       } catch (IOException e) {
         throw new UncheckedIOException(e);
       }
@@ -766,7 +770,7 @@ private interface IType {
 
     String getJavaDefaultValue();
 
-    TypeDeclaration<?> toTypeDeclaration();
+    @Nullable TypeDeclaration<?> toTypeDeclaration();
 
     String getMapper();
   }
@@ -1240,7 +1244,10 @@ public String getMapper() {
   }
 
   private static class ArrayType implements IType {
+    // it seems `name` is always filled from JSON
+    @SuppressWarnings({"NotNullFieldNotInitialized", "InstanceVariableMayNotBeInitialized"})
     private IType itemType;
+
     private final String name;
 
     public ArrayType(String name) {
@@ -1402,7 +1409,10 @@ private static void ensureFileDoesNotExists(Path file) {
     }
   }
 
-  private static String capitalize(String text) {
+  private static String capitalize(@Nullable String text) {
+    if (text == null) {
+      return "";
+    }
     return text.substring(0, 1).toUpperCase() + text.substring(1);
   }
 
@@ -1415,9 +1425,6 @@ private static String toJavaConstant(String text) {
   }
 
   private static String sanitizeJavadoc(String description) {
-    if (description == null) {
-      return null;
-    }
     // Escape */ sequences which would prematurely close the JavaDoc comment
     return description.replace("*/", "*&#47;");
   }
diff --git a/java/src/org/openqa/selenium/devtools/Command.java b/java/src/org/openqa/selenium/devtools/Command.java
index adcf87c0389e7..8aeca8f09e368 100644
--- a/java/src/org/openqa/selenium/devtools/Command.java
+++ b/java/src/org/openqa/selenium/devtools/Command.java
@@ -35,7 +35,8 @@ public Command(String method, Map<String, Object> params) {
   }
 
   public Command(String method, Map<String, Object> params, Type typeOfX) {
-    this(method, params, input -> input.read(Require.nonNull("Type to convert to", typeOfX)));
+    this(
+        method, params, input -> input.readNonNull(Require.nonNull("Type to convert to", typeOfX)));
   }
 
   public Command(String method, Map<String, Object> params, Function<JsonInput, X> mapper) {
@@ -73,7 +74,10 @@ public boolean getSendsResponse() {
   /**
    * Some CDP commands do not appear to send responses, and so are really hard to deal with. Work
    * around that by flagging those commands.
+   *
+   * @deprecated Not needed. All CDP commands return something, at least empty map.
    */
+  @Deprecated
   public Command<X> doesNotSendResponse() {
     return new Command<>(method, params, mapper, false);
   }
diff --git a/java/src/org/openqa/selenium/devtools/Connection.java b/java/src/org/openqa/selenium/devtools/Connection.java
index 7bdfb064e9d32..90194266957ab 100644
--- a/java/src/org/openqa/selenium/devtools/Connection.java
+++ b/java/src/org/openqa/selenium/devtools/Connection.java
@@ -47,6 +47,7 @@
 import java.util.function.Consumer;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import org.jspecify.annotations.Nullable;
 import org.openqa.selenium.WebDriverException;
 import org.openqa.selenium.devtools.idealized.target.model.SessionID;
 import org.openqa.selenium.internal.Either;
@@ -90,7 +91,6 @@ public Connection(HttpClient client, String url) {
   }
 
   public Connection(HttpClient client, String url, ClientConfig clientConfig) {
-    ;
     this.client = Require.nonNull("HTTP client", client);
     this.wsConfig = wsClientConfig(clientConfig, url);
     this.socket = this.client.openSocket(new HttpRequest(GET, wsConfig.baseUri()), new Listener());
@@ -117,7 +117,7 @@ private static ClientConfig wsClientConfig(ClientConfig clientConfig, String uri
     }
   }
 
-  private static class NamedConsumer<X> implements Consumer<X> {
+  private static final class NamedConsumer<X> implements Consumer<X> {
 
     private final String name;
     private final Consumer<X> delegate;
@@ -142,7 +142,7 @@ public String toString() {
     }
   }
 
-  public <X> CompletableFuture<X> send(SessionID sessionId, Command<X> command) {
+  public <X> CompletableFuture<X> send(@Nullable SessionID sessionId, Command<X> command) {
     long id = NEXT_ID.getAndIncrement();
 
     CompletableFuture<X> result = new CompletableFuture<>();
@@ -185,13 +185,16 @@ public <X> CompletableFuture<X> send(SessionID sessionId, Command<X> command) {
     socket.sendText(json);
 
     if (!command.getSendsResponse()) {
+      // As far as I see, it never happens.
+      // All DevTools commands return something - at least empty map.
+      //noinspection DataFlowIssue
       result.complete(null);
     }
 
     return result;
   }
 
-  public <X> X sendAndWait(SessionID sessionId, Command<X> command, Duration timeout) {
+  public <X> X sendAndWait(@Nullable SessionID sessionId, Command<X> command, Duration timeout) {
     try {
       CompletableFuture<X> future = send(sessionId, command);
       return future.get(timeout.toMillis(), MILLISECONDS);
diff --git a/java/src/org/openqa/selenium/devtools/ConverterFunctions.java b/java/src/org/openqa/selenium/devtools/ConverterFunctions.java
index 054b2010b5a1b..579da57223100 100644
--- a/java/src/org/openqa/selenium/devtools/ConverterFunctions.java
+++ b/java/src/org/openqa/selenium/devtools/ConverterFunctions.java
@@ -38,7 +38,7 @@ public class ConverterFunctions {
     Require.nonNull("Read callback", read);
 
     return input -> {
-      @Nullable X value = null;
+      X value = null;
 
       input.beginObject();
       while (input.hasNext()) {
diff --git a/java/src/org/openqa/selenium/devtools/DevTools.java b/java/src/org/openqa/selenium/devtools/DevTools.java
index c29fb7bc7a314..110d8530ad35b 100644
--- a/java/src/org/openqa/selenium/devtools/DevTools.java
+++ b/java/src/org/openqa/selenium/devtools/DevTools.java
@@ -32,7 +32,6 @@
 import java.util.function.Function;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.openqa.selenium.WebDriver;
 import org.openqa.selenium.devtools.idealized.Domains;
@@ -47,8 +46,8 @@ public class DevTools implements Closeable {
   private final Domains protocol;
   private final Duration timeout = Duration.ofSeconds(30);
   private final Connection connection;
-  private volatile String windowHandle;
-  private volatile SessionID cdpSession;
+  private volatile @Nullable String windowHandle;
+  private volatile @Nullable SessionID cdpSession;
 
   public DevTools(Function<DevTools, Domains> protocol, Connection connection) {
     this.connection = Require.nonNull("WebSocket connection", connection);
@@ -66,7 +65,8 @@ public void close() {
   }
 
   public void disconnectSession() {
-    if (cdpSession != null) {
+    SessionID id = cdpSession;
+    if (id != null) {
       try {
         // ensure network interception does cancel the wait for responses
         getDomains().network().disable();
@@ -75,7 +75,6 @@ public void disconnectSession() {
         LOG.log(Level.WARNING, "Exception while disabling network", e);
       }
 
-      SessionID id = cdpSession;
       cdpSession = null;
       windowHandle = null;
 
@@ -168,7 +167,7 @@ public void createSession(@Nullable String windowHandle) {
     attachToWindow(windowHandle);
   }
 
-  private void attachToWindow(String windowHandle) {
+  private void attachToWindow(@Nullable String windowHandle) {
     TargetID targetId = findTarget(windowHandle);
     attachToTarget(targetId);
     this.windowHandle = windowHandle;
@@ -210,8 +209,7 @@ private void attachToTarget(TargetID targetId) {
     }
   }
 
-  @NonNull
-  private TargetID findTarget(String windowHandle) {
+  private TargetID findTarget(@Nullable String windowHandle) {
     // Figure out the targets.
     List<TargetInfo> infos =
         connection.sendAndWait(cdpSession, getDomains().target().getTargets(), timeout);
@@ -231,6 +229,7 @@ private Throwable unwrapCause(ExecutionException e) {
     return e.getCause() != null ? e.getCause() : e;
   }
 
+  @Nullable
   public SessionID getCdpSession() {
     return cdpSession;
   }
diff --git a/java/src/org/openqa/selenium/devtools/DevToolsException.java b/java/src/org/openqa/selenium/devtools/DevToolsException.java
index ba58cb9c06d7a..eedb38062f6ec 100644
--- a/java/src/org/openqa/selenium/devtools/DevToolsException.java
+++ b/java/src/org/openqa/selenium/devtools/DevToolsException.java
@@ -17,22 +17,22 @@
 
 package org.openqa.selenium.devtools;
 
-import org.jspecify.annotations.NullMarked;
+import static java.util.Objects.requireNonNullElseGet;
+
 import org.jspecify.annotations.Nullable;
 import org.openqa.selenium.WebDriverException;
 
-@NullMarked
 public class DevToolsException extends WebDriverException {
 
-  public DevToolsException(@Nullable Throwable cause) {
-    this(cause.getMessage(), cause);
+  public DevToolsException(Throwable cause) {
+    this(requireNonNullElseGet(cause.getMessage(), cause::toString), cause);
   }
 
-  public DevToolsException(@Nullable String message) {
+  public DevToolsException(String message) {
     this(message, null);
   }
 
-  public DevToolsException(@Nullable String message, @Nullable Throwable cause) {
+  public DevToolsException(String message, @Nullable Throwable cause) {
     super(message, cause);
     addInfo(WebDriverException.DRIVER_INFO, "DevTools Connection");
   }
diff --git a/java/src/org/openqa/selenium/devtools/RequestFailedException.java b/java/src/org/openqa/selenium/devtools/RequestFailedException.java
index 322d610b28951..6ffef0c946fc3 100644
--- a/java/src/org/openqa/selenium/devtools/RequestFailedException.java
+++ b/java/src/org/openqa/selenium/devtools/RequestFailedException.java
@@ -17,7 +17,6 @@
 
 package org.openqa.selenium.devtools;
 
-import org.jspecify.annotations.NullMarked;
 import org.openqa.selenium.WebDriverException;
 import org.openqa.selenium.remote.http.Filter;
 import org.openqa.selenium.remote.http.HttpHandler;
@@ -27,5 +26,4 @@
  * browser fails to send a HTTP request. It can be caught in a {@link Filter} to handle the error
  * by, for example, returning a custom HTTP response.
  */
-@NullMarked
 public class RequestFailedException extends WebDriverException {}
diff --git a/java/src/org/openqa/selenium/devtools/events/CdpEventTypes.java b/java/src/org/openqa/selenium/devtools/events/CdpEventTypes.java
index 372c3d06687c1..a5afd71fc5fe3 100644
--- a/java/src/org/openqa/selenium/devtools/events/CdpEventTypes.java
+++ b/java/src/org/openqa/selenium/devtools/events/CdpEventTypes.java
@@ -22,6 +22,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.function.Consumer;
+import org.jspecify.annotations.Nullable;
 import org.openqa.selenium.By;
 import org.openqa.selenium.JavascriptExecutor;
 import org.openqa.selenium.WebDriver;
@@ -62,7 +63,7 @@ public void initializeListener(WebDriver webDriver) {
     };
   }
 
-  public static EventType<Void> domMutation(Consumer<DomMutationEvent> handler) {
+  public static EventType<Void> domMutation(Consumer<@Nullable DomMutationEvent> handler) {
     Require.nonNull("Handler", handler);
 
     String script = Read.resourceAsString("/org/openqa/selenium/devtools/mutation-listener.js");
diff --git a/java/src/org/openqa/selenium/devtools/events/package-info.java b/java/src/org/openqa/selenium/devtools/events/package-info.java
new file mode 100644
index 0000000000000..d5cef07efde14
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/events/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.events;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/idealized/Network.java b/java/src/org/openqa/selenium/devtools/idealized/Network.java
index 949811311a6be..2eed867917208 100644
--- a/java/src/org/openqa/selenium/devtools/idealized/Network.java
+++ b/java/src/org/openqa/selenium/devtools/idealized/Network.java
@@ -19,6 +19,7 @@
 
 import static java.net.HttpURLConnection.HTTP_OK;
 import static java.nio.charset.StandardCharsets.UTF_8;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 
 import java.net.URI;
@@ -37,6 +38,7 @@
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 import java.util.logging.Logger;
+import org.jspecify.annotations.Nullable;
 import org.openqa.selenium.Credentials;
 import org.openqa.selenium.TimeoutException;
 import org.openqa.selenium.UsernameAndPassword;
@@ -151,7 +153,6 @@ public void addAuthHandler(
     prepareToInterceptTraffic();
   }
 
-  @SuppressWarnings("SuspiciousMethodCalls")
   public void resetNetworkFilter() {
     filter = defaultFilter;
   }
@@ -216,7 +217,7 @@ public void prepareToInterceptTraffic() {
             Either<HttpRequest, HttpResponse> message = createSeMessages(pausedRequest);
 
             if (message.isRight()) {
-              HttpResponse res = message.right();
+              HttpResponse res = requireNonNull(message.right());
               CompletableFuture<HttpResponse> future = pendingResponses.remove(id);
 
               if (future == null) {
@@ -310,9 +311,9 @@ protected HttpMethod convertFromCdpHttpMethod(String method) {
 
   protected HttpResponse createHttpResponse(
       Optional<Integer> statusCode,
-      String body,
-      Boolean bodyIsBase64Encoded,
-      List<Map.Entry<String, String>> headers) {
+      @Nullable String body,
+      @Nullable Boolean bodyIsBase64Encoded,
+      List<Map.Entry<String, @Nullable String>> headers) {
     Contents.Supplier content;
 
     if (body == null) {
diff --git a/java/src/org/openqa/selenium/devtools/idealized/browser/model/package-info.java b/java/src/org/openqa/selenium/devtools/idealized/browser/model/package-info.java
new file mode 100644
index 0000000000000..6988e29b3ba26
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/idealized/browser/model/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.idealized.browser.model;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/idealized/log/model/package-info.java b/java/src/org/openqa/selenium/devtools/idealized/log/model/package-info.java
new file mode 100644
index 0000000000000..a12de4c826664
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/idealized/log/model/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.idealized.log.model;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/idealized/log/package-info.java b/java/src/org/openqa/selenium/devtools/idealized/log/package-info.java
new file mode 100644
index 0000000000000..eb8d488256630
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/idealized/log/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.idealized.log;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/idealized/package-info.java b/java/src/org/openqa/selenium/devtools/idealized/package-info.java
new file mode 100644
index 0000000000000..4dcf6a26f93db
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/idealized/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.idealized;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/idealized/runtime/model/RemoteObject.java b/java/src/org/openqa/selenium/devtools/idealized/runtime/model/RemoteObject.java
index d4f7722263de3..2dbb9630d1ac8 100644
--- a/java/src/org/openqa/selenium/devtools/idealized/runtime/model/RemoteObject.java
+++ b/java/src/org/openqa/selenium/devtools/idealized/runtime/model/RemoteObject.java
@@ -17,12 +17,14 @@
 
 package org.openqa.selenium.devtools.idealized.runtime.model;
 
+import org.jspecify.annotations.Nullable;
+
 public class RemoteObject {
 
   private final String type;
-  private final Object value;
+  private final @Nullable Object value;
 
-  public RemoteObject(String type, Object value) {
+  public RemoteObject(String type, @Nullable Object value) {
     this.type = type;
     this.value = value;
   }
@@ -38,6 +40,7 @@ public String getType() {
     return type;
   }
 
+  @Nullable
   public Object getValue() {
     return value;
   }
diff --git a/java/src/org/openqa/selenium/devtools/idealized/runtime/model/package-info.java b/java/src/org/openqa/selenium/devtools/idealized/runtime/model/package-info.java
new file mode 100644
index 0000000000000..90e68397e2e71
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/idealized/runtime/model/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.idealized.runtime.model;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/idealized/target/model/TargetInfo.java b/java/src/org/openqa/selenium/devtools/idealized/target/model/TargetInfo.java
index 6451b73b1b861..d3a54ef04961a 100644
--- a/java/src/org/openqa/selenium/devtools/idealized/target/model/TargetInfo.java
+++ b/java/src/org/openqa/selenium/devtools/idealized/target/model/TargetInfo.java
@@ -20,6 +20,7 @@
 import java.util.Optional;
 import org.openqa.selenium.Beta;
 import org.openqa.selenium.devtools.idealized.browser.model.BrowserContextID;
+import org.openqa.selenium.internal.Require;
 import org.openqa.selenium.json.JsonInput;
 
 public class TargetInfo {
@@ -42,11 +43,11 @@ public TargetInfo(
       Boolean attached,
       Optional<TargetID> openerId,
       Optional<BrowserContextID> browserContextId) {
-    this.targetId = java.util.Objects.requireNonNull(targetId, "targetId is required");
-    this.type = java.util.Objects.requireNonNull(type, "type is required");
-    this.title = java.util.Objects.requireNonNull(title, "title is required");
-    this.url = java.util.Objects.requireNonNull(url, "url is required");
-    this.attached = java.util.Objects.requireNonNull(attached, "attached is required");
+    this.targetId = Require.nonNull("targetId", targetId);
+    this.type = Require.nonNull("type", type);
+    this.title = Require.nonNull("title", title);
+    this.url = Require.nonNull("url", url);
+    this.attached = Require.nonNull("attached", attached);
     this.openerId = openerId;
     this.browserContextId = browserContextId;
   }
@@ -82,6 +83,7 @@ public Optional<BrowserContextID> getBrowserContextId() {
     return browserContextId;
   }
 
+  @SuppressWarnings("DataFlowIssue")
   private static TargetInfo fromJson(JsonInput input) {
     TargetID targetId = null;
     String type = null;
diff --git a/java/src/org/openqa/selenium/devtools/idealized/target/model/package-info.java b/java/src/org/openqa/selenium/devtools/idealized/target/model/package-info.java
new file mode 100644
index 0000000000000..de674415b30b4
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/idealized/target/model/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.idealized.target.model;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/idealized/target/package-info.java b/java/src/org/openqa/selenium/devtools/idealized/target/package-info.java
new file mode 100644
index 0000000000000..00401925522f0
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/idealized/target/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.idealized.target;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/noop/package-info.java b/java/src/org/openqa/selenium/devtools/noop/package-info.java
new file mode 100644
index 0000000000000..d59564ae18c2e
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/noop/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.noop;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/v143/BUILD.bazel b/java/src/org/openqa/selenium/devtools/v143/BUILD.bazel
index c16d20745a71e..819cfbb8ae8e4 100644
--- a/java/src/org/openqa/selenium/devtools/v143/BUILD.bazel
+++ b/java/src/org/openqa/selenium/devtools/v143/BUILD.bazel
@@ -1,3 +1,4 @@
+load("@rules_jvm_external//:defs.bzl", "artifact")
 load("//common:defs.bzl", "copy_file")
 load("//java:defs.bzl", "java_export", "java_library")
 load("//java:version.bzl", "SE_VERSION")
@@ -27,6 +28,7 @@ java_export(
         "//java/src/org/openqa/selenium:core",
         "//java/src/org/openqa/selenium/json",
         "//java/src/org/openqa/selenium/remote",
+        artifact("org.jspecify:jspecify"),
     ],
 )
 
@@ -42,6 +44,7 @@ java_library(
         "//java/src/org/openqa/selenium:core",
         "//java/src/org/openqa/selenium/json",
         "//java/src/org/openqa/selenium/remote",
+        artifact("org.jspecify:jspecify"),
     ],
 )
 
diff --git a/java/src/org/openqa/selenium/devtools/v143/package-info.java b/java/src/org/openqa/selenium/devtools/v143/package-info.java
new file mode 100644
index 0000000000000..ad7c75636057c
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/v143/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.v143;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/v144/BUILD.bazel b/java/src/org/openqa/selenium/devtools/v144/BUILD.bazel
index 885b9016ea619..19226eabfe7ca 100644
--- a/java/src/org/openqa/selenium/devtools/v144/BUILD.bazel
+++ b/java/src/org/openqa/selenium/devtools/v144/BUILD.bazel
@@ -1,3 +1,4 @@
+load("@rules_jvm_external//:defs.bzl", "artifact")
 load("//common:defs.bzl", "copy_file")
 load("//java:defs.bzl", "java_export", "java_library")
 load("//java:version.bzl", "SE_VERSION")
@@ -27,6 +28,7 @@ java_export(
         "//java/src/org/openqa/selenium:core",
         "//java/src/org/openqa/selenium/json",
         "//java/src/org/openqa/selenium/remote",
+        artifact("org.jspecify:jspecify"),
     ],
 )
 
@@ -42,6 +44,7 @@ java_library(
         "//java/src/org/openqa/selenium:core",
         "//java/src/org/openqa/selenium/json",
         "//java/src/org/openqa/selenium/remote",
+        artifact("org.jspecify:jspecify"),
     ],
 )
 
diff --git a/java/src/org/openqa/selenium/devtools/v144/package-info.java b/java/src/org/openqa/selenium/devtools/v144/package-info.java
new file mode 100644
index 0000000000000..2b3fd2eb579b6
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/v144/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.v144;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/src/org/openqa/selenium/devtools/v145/BUILD.bazel b/java/src/org/openqa/selenium/devtools/v145/BUILD.bazel
index 09605c4cd51ba..de0c2b7ccd6e6 100644
--- a/java/src/org/openqa/selenium/devtools/v145/BUILD.bazel
+++ b/java/src/org/openqa/selenium/devtools/v145/BUILD.bazel
@@ -1,3 +1,4 @@
+load("@rules_jvm_external//:defs.bzl", "artifact")
 load("//common:defs.bzl", "copy_file")
 load("//java:defs.bzl", "java_export", "java_library")
 load("//java:version.bzl", "SE_VERSION")
@@ -27,6 +28,7 @@ java_export(
         "//java/src/org/openqa/selenium:core",
         "//java/src/org/openqa/selenium/json",
         "//java/src/org/openqa/selenium/remote",
+        artifact("org.jspecify:jspecify"),
     ],
 )
 
@@ -42,6 +44,7 @@ java_library(
         "//java/src/org/openqa/selenium:core",
         "//java/src/org/openqa/selenium/json",
         "//java/src/org/openqa/selenium/remote",
+        artifact("org.jspecify:jspecify"),
     ],
 )
 
diff --git a/java/src/org/openqa/selenium/devtools/v145/package-info.java b/java/src/org/openqa/selenium/devtools/v145/package-info.java
new file mode 100644
index 0000000000000..9af117579c531
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/v145/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.v145;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/java/test/org/openqa/selenium/devtools/BUILD.bazel b/java/test/org/openqa/selenium/devtools/BUILD.bazel
index 9664a5f059000..7c0b8f68509b9 100644
--- a/java/test/org/openqa/selenium/devtools/BUILD.bazel
+++ b/java/test/org/openqa/selenium/devtools/BUILD.bazel
@@ -15,6 +15,7 @@ java_test_suite(
         "//java/src/org/openqa/selenium/remote",
         artifact("org.junit.jupiter:junit-jupiter-api"),
         artifact("org.assertj:assertj-core"),
+        artifact("org.jspecify:jspecify"),
     ] + JUNIT5_DEPS,
 )
 
@@ -46,6 +47,7 @@ java_selenium_test_suite(
         artifact("com.google.guava:guava"),
         artifact("org.junit.jupiter:junit-jupiter-api"),
         artifact("org.assertj:assertj-core"),
+        artifact("org.jspecify:jspecify"),
     ] + JUNIT5_DEPS,
 )
 
@@ -67,5 +69,6 @@ java_library(
         "//java/test/org/openqa/selenium/testing/drivers",
         artifact("org.junit.jupiter:junit-jupiter-api"),
         artifact("org.assertj:assertj-core"),
+        artifact("org.jspecify:jspecify"),
     ] + JUNIT5_DEPS,
 )
diff --git a/java/test/org/openqa/selenium/devtools/idealized/runtime/model/RemoteObjectTest.java b/java/test/org/openqa/selenium/devtools/idealized/runtime/model/RemoteObjectTest.java
new file mode 100644
index 0000000000000..951fb6130116b
--- /dev/null
+++ b/java/test/org/openqa/selenium/devtools/idealized/runtime/model/RemoteObjectTest.java
@@ -0,0 +1,57 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+package org.openqa.selenium.devtools.idealized.runtime.model;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+class RemoteObjectTest {
+  @Test
+  void toString_embracesStringValueInQuotes() {
+    assertThat(new RemoteObject("foo", "bar"))
+        .hasToString(
+            """
+            "bar"
+            """
+                .trim());
+  }
+
+  @Test
+  void toString_escapesQuotesInStringValue() {
+    assertThat(new RemoteObject("foo", "bar\"baz"))
+        .hasToString(
+            """
+            "bar\\"baz"
+            """
+                .trim());
+  }
+
+  @Test
+  void toString_withNonStringValues() {
+    assertThat(new RemoteObject("foo", 42)).hasToString("42");
+    assertThat(new RemoteObject("foo", false)).hasToString("false");
+    assertThat(new RemoteObject("foo", List.of("a", "b", "c"))).hasToString("[a, b, c]");
+  }
+
+  @Test
+  void toString_withNullValue() {
+    assertThat(new RemoteObject("foo", null)).hasToString("null");
+  }
+}
diff --git a/java/test/org/openqa/selenium/devtools/idealized/runtime/model/package-info.java b/java/test/org/openqa/selenium/devtools/idealized/runtime/model/package-info.java
new file mode 100644
index 0000000000000..90e68397e2e71
--- /dev/null
+++ b/java/test/org/openqa/selenium/devtools/idealized/runtime/model/package-info.java
@@ -0,0 +1,21 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you 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.
+
+@NullMarked
+package org.openqa.selenium.devtools.idealized.runtime.model;
+
+import org.jspecify.annotations.NullMarked;