@Override
  public boolean equals(Object that) {
    if (that == null)
      return false;
    if (that instanceof TableIdentifier)
      return this.equals((TableIdentifier)that);
    return false;
  }
Returns true if field corresponding to fieldID is set (has been assigned a value) and false otherwise
iceberg/iceberg-handler/src/main/java/org/apache/iceberg/mr/hive/compaction/evaluator/amoro/TableIdentifier.java