@Override
  public RemoteOperation newRemoteOperation(MasterProcedureEnv env) {
    return new RegionCloseOperation(this, region, getProcId(), assignCandidate, isSplit,
      env.getMasterServices().getMasterActiveTime());
  }
The remote procedure used to close a region.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/CloseRegionProcedure.java