@Override
  public Collection<ResourcePermission> getRequiredPermissions(String regionName) {
    return Collections.singletonList(new ResourcePermission(ResourcePermission.Resource.DATA,
        ResourcePermission.Operation.READ, regionName));
  }
{@link WaitUntilFlushedFunction} will check all the members with index to wait until the events
in current AEQs are flushed into index. This function enables an accessor and client to call to
make sure the current events are processed.
geode-lucene/src/main/java/org/apache/geode/cache/lucene/internal/distributed/WaitUntilFlushedFunction.java