private void assignLongNullsRepeating(int keyIndex, int index, int size,
      LongColumnVector columnVector) {
    for(int r = 0; r < size; ++r) {
      vectorHashKeyWrappers[r].assignNullLong(keyIndex, index);
    }
  }
Helper method to assign values from a vector column into the key wrapper.
Optimized for double type, repeating nulls.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/wrapper/VectorHashKeyWrapperBatch.java