code: @Override
    public byte[] toBytes(TaskKey taskKey) {
      return Bytes.add(jobKeyConv.toBytes(taskKey), Constants.SEP_BYTES,
          Bytes.toBytes(taskKey.getTaskId()));
    }
docs: Returns the bytes representation for a TaskKey.
  
  @param taskKey
  the TaskKey instance to serialize
  @return the serialized representation of the TaskKey