code: @Override
    public byte[] call(final byte[] memento) {
      LOG.log(Level.INFO, "RUN: command: {0}", this.command);
      final String result = CommandUtils.runCommand(this.command);
      LOG.log(Level.INFO, "RUN: result: {0}", result);
      return CODEC.encode(result);
    }
docs: Execute the shell command and return the result, which is sent back to
  the JobDriver and surfaced in the CompletedTask object.
  
  @param memento ignored.
  @return byte string containing the stdout from executing the shell command.