@Explain(displayName = "partitions", explainLevels = { Level.USER, Level.DEFAULT, Level.EXTENDED })
  public Map<String, String> getPartitionSpecs() {
    return partitionSpecs;
  }
DDL task description for ALTER TABLE ... EXCHANGE PARTITION ... WITH TABLE ... commands.
ql/src/java/org/apache/hadoop/hive/ql/ddl/table/partition/exchange/AlterTableExchangePartitionsDesc.java