@Override
  protected void serializeStateData(ProcedureStateSerializer serializer) throws IOException {
    super.serializeStateData(serializer);
    serializer
      .serialize(SnapshotProcedureStateData.newBuilder().setSnapshot(this.snapshot).build());
  }
A procedure used to take snapshot on tables.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/SnapshotProcedure.java