@Explain(displayName="principal desc", explainLevels = { Level.USER, Level.DEFAULT, Level.EXTENDED })
  public PrincipalDesc getPrincipalDesc() {
    return principal;
  }
DDL task description for SHOW GRANT commands.
ql/src/java/org/apache/hadoop/hive/ql/ddl/privilege/show/grant/ShowGrantDesc.java