@org.apache.thrift.annotation.Nullable
  public Object getFieldValue(_Fields field) {
    switch (field) {
    case CATALOG:
      return getCatalog();

    case DATABASE:
      return getDatabase();

    case TABLE_NAME:
      return getTableName();

    }
    throw new IllegalStateException();
  }
Returns true if field tableName 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