address feedback: use guava for overflow math & codacy tweaks

Author: igorbernstein2

google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/gaxx/reframing/ReframingResponseObserver.java

@@ -20,6 +20,7 @@
 import com.google.api.gax.rpc.StateCheckingResponseObserver;
 import com.google.api.gax.rpc.StreamController;
 import com.google.common.base.Preconditions;
+import com.google.common.math.IntMath;
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
@@ -159,10 +160,8 @@ private void onRequest(int count) {
       if (current == Integer.MAX_VALUE) {
         return;
       }
-      // Prevent overflow
-      int maxRequest = Integer.MAX_VALUE - current;
-      int newValue = maxRequest > count ? current + count : Integer.MAX_VALUE;
 
+      int newValue = IntMath.saturatedAdd(current, count);
       if (numRequested.compareAndSet(current, newValue)) {
         break;
       }

google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/gaxx/reframing/ReframingResponseObserverTest.java

@@ -320,7 +320,7 @@ public void testReframerPushError() throws Exception {
         new DasherizingReframer(1) {
           @Override
           public void push(String response) {
-            if (response.equals("boom")) {
+            if ("boom".equals(response)) {
               throw new IllegalStateException("fake error");
             }
             super.push(response);

google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/gaxx/testing/FakeStreamingApi.java

@@ -120,7 +120,7 @@ public static class ServerStreamingStashCallable<RequestT, ResponseT>
     private ResponseObserver<ResponseT> actualObserver;
     private RequestT actualRequest;
     private List<ResponseT> responseList;
-    private BlockingQueue<StreamControllerStash<ResponseT>> calls = Queues.newLinkedBlockingQueue();
+    private final BlockingQueue<StreamControllerStash<ResponseT>> calls = Queues.newLinkedBlockingQueue();
 
     public ServerStreamingStashCallable() {
       responseList = new ArrayList<>();