@Override
    public List<Object> getCurrentKey() throws HiveException {
      List<Object> deserializedList =
          MapJoinKey.deserializeRow(
              keyRef.getBytes(),
              (int) keyRef.getOffset(),
              keyRef.getLength(),
              bytesWritable, keySerde);
      return deserializedList;
    }
For FULL OUTER MapJoin: Iterates through the Small Table hash table and returns the key and
value rows for any non-matched keys.
ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/MapJoinBytesTableContainer.java