public void addToOpen_txns(long elem) {
    if (this.open_txns == null) {
      this.open_txns = new java.util.ArrayList<java.lang.Long>();
    }
    this.open_txns.add(elem);
  }
Returns true if field txn_high_water_mark is set (has been assigned a value) and false otherwise
standalone-metastore/metastore-common/src/gen/thrift/gen-javabean/org/apache/hadoop/hive/metastore/api/GetOpenTxnsResponse.java