public static void checkQueueSizeInStats(String senderId, final int expectedQueueSize) {
    AbstractGatewaySender sender = (AbstractGatewaySender) cache.getGatewaySender(senderId);
    GatewaySenderStats statistics = sender.getStatistics();
    await().untilAsserted(() -> assertThat(statistics.getEventQueueSize())
        .isEqualTo(expectedQueueSize));
  }
Returns a Map that contains the count for number of cache server and number of Receivers.
geode-wan/src/distributedTest/java/org/apache/geode/internal/cache/wan/WANTestBase.java