@AfterClass
  public static void tearDownAfterClass() throws Exception {
    Closeables.close(REGISTRY, true);
    UTIL.shutdownMiniCluster();
  }
Make sure that we can update the bootstrap server from master to region server, and region server
could also contact each other to update the bootstrap nodes.
hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestBootstrapNodeUpdate.java