@Override
  public CompletableFuture<String> getClusterId() {
    return CompletableFuture.completedFuture(endpoint.getClusterId());
  }
A {@link ConnectionRegistry} implementation used at server side, where we could use the
{@link ConnectionRegistryEndpoint} directly, without any rpcs.
hbase-server/src/main/java/org/apache/hadoop/hbase/client/ShortCircuitConnectionRegistry.java