@Override
  public void start(CoprocessorEnvironment env) throws IOException {
    if (!(env instanceof HasMasterServices)) {
      throw new IOException("Does not implement HMasterServices");
    }
    master = ((HasMasterServices) env).getMasterServices();
    groupAdminService.initialize(master);
  }
@deprecated Keep it here only for compatibility with old client, all the logics have been moved
            into core of HBase.
hbase-server/src/main/java/org/apache/hadoop/hbase/rsgroup/RSGroupAdminEndpoint.java