private SpyAsyncEventListener getSpyAsyncEventListener() {
    return (SpyAsyncEventListener) getAsyncEventListener();
  }
Regression test for TRAC #50366: NullPointerException with AsyncEventQueue#size() when number
of dispatchers is more than 1
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/wan/asyncqueue/ConcurrentAsyncEventListenerDistributedTest.java