public static AsyncClusterConnection createAsyncClusterConnection(Configuration conf,
    SocketAddress localAddress, User user) throws IOException {
    return createAsyncClusterConnection(conf, ConnectionRegistryFactory.create(conf, user),
      localAddress, user);
  }
Create a new {@link AsyncClusterConnection} instance.
<p/>
Unlike what we have done in {@link ConnectionFactory}, here we just return an
{@link AsyncClusterConnection} instead of a {@link java.util.concurrent.CompletableFuture},
which means this method could block on fetching the cluster id. This is just used to simplify
the implementation, as when starting new region servers, we do not need to be event-driven. Can
change later if we want a {@link java.util.concurrent.CompletableFuture} here.
hbase-server/src/main/java/org/apache/hadoop/hbase/client/ClusterConnectionFactory.java