public boolean isDistanceGreater(Object l1, Object l2, int amt) {
      throw new UnsupportedOperationException("Only unbounded ranges supported");
    }
Simply returns the Object[] returned by VectorPTFGroupBatches.getAt(i), which contains the
value of the ordering columns.
ql/src/java/org/apache/hadoop/hive/ql/udf/ptf/ValueBoundaryScanner.java