public boolean isSet(_Fields field) {
    if (field == null) {
      throw new IllegalArgumentException();
    }

    switch (field) {
    case CATALOG:
      return isSetCatalog();
    case DATABASE:
      return isSetDatabase();
    case TABLE_NAME:
      return isSetTableName();
    }
    throw new IllegalStateException();
  }
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