Remove "experimental API" warnings from members in the .NET protobuf runtime.

PiperOrigin-RevId: 736777274

Author: protobuf-github-bot

csharp/src/Google.Protobuf/Extension.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 //
@@ -12,8 +12,12 @@
 namespace Google.Protobuf
 {
     /// <summary>
-    /// Represents a non-generic extension definition. This API is experimental and subject to change.
+    /// Represents a non-generic extension definition.
     /// </summary>
+    /// <remarks>
+    /// Most users will not use this abstract class directly, instead using the generated instances
+    /// of the concrete subclasses.
+    /// </remarks>
     public abstract class Extension
     {
         internal abstract Type TargetType { get; }
@@ -37,8 +41,7 @@ protected Extension(int fieldNumber)
     }
 
     /// <summary>
-    /// Represents a type-safe extension identifier used for getting and setting single extension values in <see cref="IExtendableMessage{T}"/> instances. 
-    /// This API is experimental and subject to change.
+    /// Represents a type-safe extension identifier used for getting and setting single extension values in <see cref="IExtendableMessage{T}"/> instances.
     /// </summary>
     /// <typeparam name="TTarget">The message type this field applies to</typeparam>
     /// <typeparam name="TValue">The field value type of this extension</typeparam>
@@ -68,7 +71,6 @@ internal override IExtensionValue CreateValue()
 
     /// <summary>
     /// Represents a type-safe extension identifier used for getting repeated extension values in <see cref="IExtendableMessage{T}"/> instances.
-    /// This API is experimental and subject to change.
     /// </summary>
     /// <typeparam name="TTarget">The message type this field applies to</typeparam>
     /// <typeparam name="TValue">The repeated field value type of this extension</typeparam>

csharp/src/Google.Protobuf/ExtensionRegistry.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 //
@@ -15,7 +15,7 @@
 namespace Google.Protobuf
 {
     /// <summary>
-    /// Provides extensions to messages while parsing. This API is experimental and subject to change.
+    /// Provides extensions to messages while parsing.
     /// </summary>
     public sealed class ExtensionRegistry : ICollection<Extension>, IDeepCloneable<ExtensionRegistry>
     {

csharp/src/Google.Protobuf/ExtensionSet.cs

@@ -18,9 +18,14 @@ namespace Google.Protobuf
 {
     /// <summary>
     /// Methods for managing <see cref="ExtensionSet{TTarget}"/>s with null checking.
-    /// 
-    /// Most users will not use this class directly and its API is experimental and subject to change.
     /// </summary>
+    /// <remarks>
+    /// Most users will not use this class directly. Accessing extensions for a given message
+    /// is usually performed by obtaining the generated instance of
+    /// <see cref="Extension{TTarget,TValue}"/> or <see cref="RepeatedExtension{TTarget,TValue}"/>
+    /// and then calling methods on <see cref="IExtendableMessage{T}"/> (which is implemented by
+    /// all generated messages).
+    /// </remarks>
     public static class ExtensionSet
     {
         private static bool TryGetValue<TTarget>(ref ExtensionSet<TTarget> set, Extension extension, out IExtensionValue value) where TTarget : IExtendableMessage<TTarget>

csharp/src/Google.Protobuf/UnsafeByteOperations.cs

@@ -1,4 +1,4 @@
-#region Copyright notice and license
+#region Copyright notice and license
 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 //
@@ -48,7 +48,6 @@ public static class UnsafeByteOperations
         /// <summary>
         /// Constructs a new <see cref="ByteString" /> from the given bytes. The bytes are not copied,
         /// and must not be modified while the <see cref="ByteString" /> is in use.
-        /// This API is experimental and subject to change.
         /// </summary>
         public static ByteString UnsafeWrap(ReadOnlyMemory<byte> bytes)
         {