@Test(expected = ExecutionException.class)
 public void testReplaceAsyncOperationThrowsExceptionWhenQuorumSizeNotMet() throws Exception {
   Future<Boolean> foo = cache4.replaceAsync(1, "");
   foo.get();
 }
 @Test
 public void testReplaceAsyncOperationSuccessfulWhenQuorumSizeMet() throws Exception {
   Future<Boolean> foo = cache1.replaceAsync(1, "");
   foo.get();
 }