public GatewaySenderEventImpl addEvent(Object key) {
    bucketRegionQueue.getEventTracker().setInitialized();
    bucketRegionQueue.entries.disableLruUpdateCallback();
    GatewaySenderEventImpl event = mock(GatewaySenderEventImpl.class);
    bucketRegionQueue.entries.initialImagePut(key, 0, event, false, false, null, null, false);
    bucketRegionQueue.entries.enableLruUpdateCallback();
    return event;
  }
Helper class in the internal cache package to access protected BucketRegionQueue methods.
geode-core/src/test/java/org/apache/geode/internal/cache/BucketRegionQueueHelper.java