@Explain(displayName = "new columns", explainLevels = { Level.USER, Level.DEFAULT, Level.EXTENDED })
  public List<String> getNewColsString() {
    return Utilities.getFieldSchemaString(newColumns);
  }
DDL task description for ALTER TABLE ... ADD COLUMNS ... commands.
ql/src/java/org/apache/hadoop/hive/ql/ddl/table/column/add/AlterTableAddColumnsDesc.java