more visibility fixes

Author: igorbernstein2

gax-grpc/src/main/java/com/google/api/gax/grpc/GrpcExceptionServerStreamingCallable.java

@@ -71,7 +71,7 @@ public ExceptionResponseObserver(ResponseObserver<ResponseT> innerObserver) {
     }
 
     @Override
-    public void onStartImpl(final StreamController controller) {
+    protected void onStartImpl(final StreamController controller) {
       innerObserver.onStart(
           new StreamController() {
             @Override
@@ -93,12 +93,12 @@ public void request(int count) {
     }
 
     @Override
-    public void onResponseImpl(ResponseT response) {
+    protected void onResponseImpl(ResponseT response) {
       innerObserver.onResponse(response);
     }
 
     @Override
-    public void onErrorImpl(Throwable t) {
+    protected void onErrorImpl(Throwable t) {
       if (cancellationException != null) {
         t = cancellationException;
       } else {
@@ -108,7 +108,7 @@ public void onErrorImpl(Throwable t) {
     }
 
     @Override
-    public void onCompleteImpl() {
+    protected void onCompleteImpl() {
       innerObserver.onComplete();
     }
   }

gax-grpc/src/test/java/com/google/api/gax/grpc/GrpcDirectServerStreamingCallableTest.java

@@ -206,20 +206,20 @@ public void testObserverErrorCancelsCall() throws Throwable {
     ResponseObserver<Money> moneyObserver =
         new AbstractResponseObserver<Money>() {
           @Override
-          public void onStartImpl(StreamController controller) {}
+          protected void onStartImpl(StreamController controller) {}
 
           @Override
-          public void onResponseImpl(Money response) {
+          protected void onResponseImpl(Money response) {
             throw expectedCause;
           }
 
           @Override
-          public void onErrorImpl(Throwable t) {
+          protected void onErrorImpl(Throwable t) {
             actualErrorF.set(t);
           }
 
           @Override
-          public void onCompleteImpl() {
+          protected void onCompleteImpl() {
             actualErrorF.set(null);
           }
         };
@@ -262,27 +262,27 @@ private static class MoneyObserver extends AbstractResponseObserver<Money> {
     }
 
     @Override
-    public void onStartImpl(StreamController controller) {
+    protected void onStartImpl(StreamController controller) {
       this.controller = controller;
       if (!autoFlowControl) {
         controller.disableAutoInboundFlowControl();
       }
     }
 
     @Override
-    public void onResponseImpl(Money value) {
+    protected void onResponseImpl(Money value) {
       response = value;
       latch.countDown();
     }
 
     @Override
-    public void onErrorImpl(Throwable t) {
+    protected void onErrorImpl(Throwable t) {
       error = t;
       latch.countDown();
     }
 
     @Override
-    public void onCompleteImpl() {
+    protected void onCompleteImpl() {
       completed = true;
       latch.countDown();
     }