@Override
  public HCatEventMessage checkValid() {
    if (getTable() == null)
      throw new IllegalStateException("Table name unset.");
    if (getPartitions() == null)
      throw new IllegalStateException("Partition-list unset.");
    return super.checkValid();
  }
HCat message sent when a partition is dropped in HCatalog.
hcatalog/server-extensions/src/main/java/org/apache/hive/hcatalog/messaging/DropPartitionMessage.java