public DockerKillCommand setSignal(String signal) {
    super.addCommandArguments("signal", signal);
    return this;
  }
@Test
  public void testSetGracePeriod() {
    dockerKillCommand.setSignal(SIGNAL);
    assertEquals("kill", StringUtils.join(",",
        dockerKillCommand.getDockerCommandWithArguments()
            .get("docker-command")));
    assertEquals("foo", StringUtils.join(",",
        dockerKillCommand.getDockerCommandWithArguments().get("name")));
    assertEquals("SIGUSR2", StringUtils.join(",",
        dockerKillCommand.getDockerCommandWithArguments().get("signal")));
    assertEquals(3, dockerKillCommand.getDockerCommandWithArguments().size());
  }