FutureCallback<String> callback =
        new FutureCallback<String>() {
          private boolean called = false;

          @Override
          public void onSuccess(String result) {
            fail("Was not expecting onSuccess() to be called.");
          }

          @Override
          public synchronized void onFailure(Throwable t) {
            assertFalse(called);

    FutureCallback<String> callback =
        new FutureCallback<String>() {
          private boolean called = false;

          @Override
          public void onSuccess(String result) {
            fail("Was not expecting onSuccess() to be called.");
          }

          @Override
          public synchronized void onFailure(Throwable t) {
            assertFalse(called);