public BytesRefWritable get(int index) {
    if (index >= valid) {
      throw new IndexOutOfBoundsException(
          "This BytesRefArrayWritable only has " + valid + " valid values.");
    }
    return bytesRefWritables[index];
  }
Gets the BytesRefWritable at the specified position. Make sure the position
is valid by first call resetValid.

@param index
         the position index, starting from zero
@throws IndexOutOfBoundsException
serde/src/java/org/apache/hadoop/hive/serde2/columnar/BytesRefArrayWritable.java