public static <K> Map<String, List<K>> checkQueue_BR(String senderId, int numBuckets) {
    GatewaySender sender = getGatewaySender(senderId);
    RegionQueue parallelQueue =
        ((AbstractGatewaySender) sender).getQueues().toArray(new RegionQueue[1])[0];

    PartitionedRegion region = (PartitionedRegion) parallelQueue.getRegion();
    Map<String, List<K>> listenerAttrs = new HashMap<>();
    for (int i = 0; i < numBuckets; i++) {
      BucketRegion br = region.getBucketRegion(i);
      if (br != null) {
        @SuppressWarnings("unchecked")
        QueueListener<K, ?> listener = (QueueListener<K, ?>) br.getCacheListener();
        if (listener != null) {
          listenerAttrs.put("Create" + i, listener.createList);
          listenerAttrs.put("Update" + i, listener.updateList);
          listenerAttrs.put("Destroy" + i, listener.destroyList);
        }
      }
    }
    return listenerAttrs;
  }
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