public DeleteSubRecord getDeleteSubRecord() {
    if (subRecord.getType().equals(SubRecord.Type.DELETE)) {
      return (DeleteSubRecord) subRecord;
    }
    return null;
  }
@return the delete record if type is {@link SubRecord.Type#DELETE}. {@code null} otherwise.
ambry-messageformat/src/main/java/com/github/ambry/messageformat/UpdateRecord.java