Add sample code link to README and fix MissingSdkAnnotationCheck to check interface

Author: zoewangg

README.md

@@ -11,6 +11,7 @@ artifact source.
 
 * [SDK Homepage][sdk-website]
 * [1.11 to 2.0 Changelog](docs/LaunchChangelog.md)
+* [Sample Code](#sample-code)
 * [API Docs][docs-api]
 * [Developer Guide][docs-guide] ([source][docs-guide-source])
 * [Issues][sdk-issues]
@@ -111,13 +112,18 @@ See the [Set up the AWS SDK for Java][docs-setup] section of the developer guide
 
 ## Building From Source
 
-Once you check out the code from GitHub, you can build it using Maven. To disable the GPG-signing
-in the build, use:
+Once you check out the code from GitHub, you can build it using Maven.
 
 ```sh
-mvn clean install -Dgpg.skip=true
+mvn clean install
 ```
 
+## Sample Code
+You can find sample code for v2 in the following places:
+
+* [aws-doc-sdk-examples] repo.
+* Integration tests in this repo. They are located in the `it` directory under each service module, eg: [s3-integration-tests]
+
 ## Giving Feedback
 We need your help in making this SDK great. Please participate in the community and contribute to this effort by submitting issues, participating in discussion forums and submitting pull requests through the following channels.
 
@@ -145,3 +151,5 @@ We need your help in making this SDK great. Please participate in the community
 [support-center]: https://console.aws.amazon.com/support/
 [console]: https://console.aws.amazon.com
 [bom]: http://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22software.amazon.awssdk%22%20AND%20a%3A%22bom%22
+[aws-doc-sdk-examples]: https://github.com/awsdocs/aws-doc-sdk-examples/tree/master/javav2
+[s3-integration-tests]: https://github.com/aws/aws-sdk-java-v2/tree/master/services/s3/src/it/java/software/amazon/awssdk/services/s3

build-tools/src/main/java/software/amazon/awssdk/buildtools/checkstyle/MissingSdkAnnotationCheck.java

@@ -43,12 +43,13 @@ public int[] getAcceptableTokens() {
     @Override
     public int[] getRequiredTokens() {
         return new int[] {
-            TokenTypes.CLASS_DEF
+            TokenTypes.CLASS_DEF,
+            TokenTypes.INTERFACE_DEF
         };
     }
 
     @Override
-    public void visitToken(final DetailAST ast) {
+    public void visitToken(DetailAST ast) {
         if (!ScopeUtils.isOuterMostType(ast) || SDK_ANNOTATIONS.stream().anyMatch(a -> AnnotationUtility.containsAnnotation
             (ast, a))) {
             return;

core/aws-core/src/main/java/software/amazon/awssdk/awscore/eventstream/EventStreamResponseHandler.java

@@ -21,8 +21,10 @@
 import org.reactivestreams.Publisher;
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
+import software.amazon.awssdk.annotations.SdkProtectedApi;
 import software.amazon.awssdk.core.async.SdkPublisher;
 
+@SdkProtectedApi
 public interface EventStreamResponseHandler<ResponseT, EventT> {
 
     /**

core/protocols/aws-json-protocol/src/main/java/software/amazon/awssdk/protocols/json/internal/dom/SdkJsonNode.java

@@ -17,10 +17,12 @@
 
 import java.util.List;
 import java.util.Map;
+import software.amazon.awssdk.annotations.SdkInternalApi;
 
 /**
  * DOM interface for reading a JSON document.
  */
+@SdkInternalApi
 public interface SdkJsonNode {
 
     /**

core/sdk-core/src/main/java/software/amazon/awssdk/core/internal/http/TransformingAsyncResponseHandler.java

@@ -16,13 +16,15 @@
 package software.amazon.awssdk.core.internal.http;
 
 import java.util.concurrent.CompletableFuture;
+import software.amazon.awssdk.annotations.SdkInternalApi;
 import software.amazon.awssdk.http.async.SdkAsyncHttpResponseHandler;
 
 /**
  * A response handler that returns a transformed response.
  *
  * @param <ResultT> The type of the result.
  */
+@SdkInternalApi
 public interface TransformingAsyncResponseHandler<ResultT> extends SdkAsyncHttpResponseHandler {
     /**
      * Return the future holding the transformed response.