long getElementsHigherThan(Map<KeyWrapper, VectorAggregationBufferRow> aggMap, int avgAccess) {
    return aggMap.values().stream().filter(v -> (v.getAccessCount() > avgAccess)).count();
  }
Unit test for the vectorized GROUP BY operator.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/TestVectorGroupByOperator.java