code: public void shutdown(ExecutorID executorId) {
      Builder shutdown = build().setShutdown(Shutdown.newBuilder().setExecutorId(executorId));
      sendCall(shutdown, Type.SHUTDOWN);
    }
docs: Sent by the scheduler to shutdown a specific custom executor. When an executor gets a shutdown event,
  it is expected to kill all its tasks (and send TASK_KILLED updates) and terminate. If an executor
  doesn’t terminate within a certain timeout, the agent will forcefully destroy the container
  (executor and its tasks) and transition its active tasks to TASK_LOST.
  
  @param executorId