@Signature
  @Explain(displayName = "Number of rows", explainLevels = { Level.USER, Level.DEFAULT, Level.EXTENDED })
  public int getLimit() {
    return limit;
  }
not to print the offset if it is 0 we need to turn null.
use Integer instead of int.
ql/src/java/org/apache/hadoop/hive/ql/plan/LimitDesc.java