cronet: Update to Java-8 API's and tighten the scopes

cronet/src/main/java/io/grpc/cronet/CronetChannelBuilder.java

@@ -84,7 +84,7 @@ public static CronetChannelBuilder forAddress(String name, int port) {
 
   private final CronetEngine cronetEngine;
   private final ManagedChannelImplBuilder managedChannelImplBuilder;
-  private TransportTracer.Factory transportTracerFactory = TransportTracer.getDefaultFactory();
+  private final TransportTracer.Factory transportTracerFactory = TransportTracer.getDefaultFactory();
 
   private boolean alwaysUsePut = false;
 
@@ -132,7 +132,7 @@ protected ManagedChannelBuilder<?> delegate() {
    * Sets the maximum message size allowed to be received on the channel. If not called,
    * defaults to {@link io.grpc.internal.GrpcUtil#DEFAULT_MAX_MESSAGE_SIZE}.
    */
-  public final CronetChannelBuilder maxMessageSize(int maxMessageSize) {
+  public CronetChannelBuilder maxMessageSize(int maxMessageSize) {
     checkArgument(maxMessageSize >= 0, "maxMessageSize must be >= 0");
     this.maxMessageSize = maxMessageSize;
     return this;
@@ -141,7 +141,7 @@ public final CronetChannelBuilder maxMessageSize(int maxMessageSize) {
   /**
    * Sets the Cronet channel to always use PUT instead of POST. Defaults to false.
    */
-  public final CronetChannelBuilder alwaysUsePut(boolean enable) {
+  public CronetChannelBuilder alwaysUsePut(boolean enable) {
     this.alwaysUsePut = enable;
     return this;
   }
@@ -163,7 +163,7 @@ public final CronetChannelBuilder alwaysUsePut(boolean enable) {
    *     application.
    * @return the builder to facilitate chaining.
    */
-  final CronetChannelBuilder setTrafficStatsTag(int tag) {
+  CronetChannelBuilder setTrafficStatsTag(int tag) {
     trafficStatsTagSet = true;
     trafficStatsTag = tag;
     return this;
@@ -184,7 +184,7 @@ final CronetChannelBuilder setTrafficStatsTag(int tag) {
    * @param uid the UID to attribute socket traffic caused by this channel.
    * @return the builder to facilitate chaining.
    */
-  final CronetChannelBuilder setTrafficStatsUid(int uid) {
+  CronetChannelBuilder setTrafficStatsUid(int uid) {
     trafficStatsUidSet = true;
     trafficStatsUid = uid;
     return this;
@@ -200,7 +200,7 @@ final CronetChannelBuilder setTrafficStatsUid(int uid) {
    *
    * @since 1.12.0
    */
-  public final CronetChannelBuilder scheduledExecutorService(
+  public CronetChannelBuilder scheduledExecutorService(
       ScheduledExecutorService scheduledExecutorService) {
     this.scheduledExecutorService =
         checkNotNull(scheduledExecutorService, "scheduledExecutorService");

cronet/src/main/java/io/grpc/cronet/CronetClientStream.java

@@ -247,7 +247,7 @@ public void cancel(Status reason) {
   class TransportState extends Http2ClientStreamTransportState {
     private final Object lock;
     @GuardedBy("lock")
-    private Collection<PendingData> pendingData = new ArrayList<PendingData>();
+    private final Collection<PendingData> pendingData = new ArrayList<>();
     @GuardedBy("lock")
     private boolean streamReady;
     @GuardedBy("lock")

cronet/src/main/java/io/grpc/cronet/CronetClientTransport.java

@@ -56,14 +56,15 @@ class CronetClientTransport implements ConnectionClientTransport {
   private final Object lock = new Object();
   @GuardedBy("lock")
   private final Set<CronetClientStream> streams = Collections.newSetFromMap(
-          new IdentityHashMap<CronetClientStream, Boolean>());
+          new IdentityHashMap<>());
   private final Executor executor;
   private final int maxMessageSize;
   private final boolean alwaysUsePut;
   private final TransportTracer transportTracer;
   private Attributes attrs;
   private final boolean useGetForSafeMethods;
   private final boolean usePutForIdempotentMethods;
+  private final StreamBuilderFactory streamFactory;
   // Indicates the transport is in go-away state: no new streams will be processed,
   // but existing streams may continue.
   @GuardedBy("lock")
@@ -79,7 +80,6 @@ class CronetClientTransport implements ConnectionClientTransport {
   @GuardedBy("lock")
   // Whether this transport has started.
   private boolean started;
-  private StreamBuilderFactory streamFactory;
 
   CronetClientTransport(
       StreamBuilderFactory streamFactory,
@@ -205,9 +205,9 @@ public void shutdownNow(Status status) {
       // streams.remove()
       streamsCopy = new ArrayList<>(streams);
     }
-    for (int i = 0; i < streamsCopy.size(); i++) {
+    for (CronetClientStream cronetClientStream : streamsCopy) {
       // Avoid deadlock by calling into stream without lock held
-      streamsCopy.get(i).cancel(status);
+      cronetClientStream.cancel(status);
     }
     stopIfNecessary();
   }
@@ -255,7 +255,7 @@ public InternalLogId getLogId() {
    */
   void stopIfNecessary() {
     synchronized (lock) {
-      if (goAway && !stopped && streams.size() == 0) {
+      if (goAway && !stopped && streams.isEmpty()) {
         stopped = true;
       } else {
         return;

cronet/src/test/java/io/grpc/cronet/CronetClientStreamTest.java

@@ -80,12 +80,7 @@ public final class CronetClientStreamTest {
   @Mock private BidirectionalStream.Builder builder;
   private final Object lock = new Object();
   private final TransportTracer transportTracer = TransportTracer.getDefaultFactory().create();
-  private final Executor executor = new Executor() {
-      @Override
-      public void execute(Runnable r) {
-        r.run();
-      }
-    };
+  private final Executor executor = Runnable::run;
   CronetClientStream clientStream;
 
   private MethodDescriptor.Marshaller<Void> marshaller = TestMethodDescriptors.voidMarshaller();
@@ -171,7 +166,7 @@ public void write() {
     String[] requests = new String[5];
     WritableBuffer[] buffers = new WritableBuffer[5];
     for (int i = 0; i < 5; ++i) {
-      requests[i] = new String("request" + String.valueOf(i));
+      requests[i] = "request" + i;
       buffers[i] = allocator.allocate(requests[i].length());
       buffers[i].write(requests[i].getBytes(Charset.forName("UTF-8")), 0, requests[i].length());
       // The 3rd and 5th writeFrame calls have flush=true.
@@ -206,27 +201,19 @@ public void write() {
   }
 
   private static List<Map.Entry<String, String>> responseHeader(String status) {
-    Map<String, String> headers = new HashMap<String, String>();
+    Map<String, String> headers = new HashMap<>();
     headers.put(":status", status);
     headers.put("content-type", "application/grpc");
     headers.put("test-key", "test-value");
-    List<Map.Entry<String, String>> headerList = new ArrayList<Map.Entry<String, String>>(3);
-    for (Map.Entry<String, String> entry : headers.entrySet()) {
-      headerList.add(entry);
-    }
-    return headerList;
+    return new ArrayList<>(headers.entrySet());
   }
 
   private static List<Map.Entry<String, String>> trailers(int status) {
-    Map<String, String> trailers = new HashMap<String, String>();
+    Map<String, String> trailers = new HashMap<>();
     trailers.put("grpc-status", String.valueOf(status));
     trailers.put("content-type", "application/grpc");
     trailers.put("test-trailer-key", "test-trailer-value");
-    List<Map.Entry<String, String>> trailerList = new ArrayList<Map.Entry<String, String>>(3);
-    for (Map.Entry<String, String> entry : trailers.entrySet()) {
-      trailerList.add(entry);
-    }
-    return trailerList;
+    return new ArrayList<>(trailers.entrySet());
   }
 
   private static ByteBuffer createMessageFrame(byte[] bytes) {

cronet/src/test/java/io/grpc/cronet/CronetClientTransportTest.java

@@ -71,12 +71,7 @@ public final class CronetClientTransportTest {
   private MethodDescriptor<Void, Void> descriptor = TestMethodDescriptors.voidMethod();
   @Mock private ManagedClientTransport.Listener clientTransportListener;
   @Mock private BidirectionalStream.Builder builder;
-  private final Executor executor = new Executor() {
-      @Override
-      public void execute(Runnable r) {
-        r.run();
-      }
-    };
+  private final Executor executor = Runnable::run;
 
   @Before
   public void setUp() {