@Override
  protected void serializeStateData(ProcedureStateSerializer serializer) throws IOException {
    super.serializeStateData(serializer);
    CloseRegionProcedureStateData.Builder builder = CloseRegionProcedureStateData.newBuilder();
    if (assignCandidate != null) {
      builder.setAssignCandidate(ProtobufUtil.toServerName(assignCandidate));
    }
    builder.setEvictCache(isSplit);
    serializer.serialize(builder.build());
  }
The remote procedure used to close a region.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/CloseRegionProcedure.java