code: public ProcessExecutor destroyer(ProcessDestroyer destroyer) {
      removeListeners(DestroyerListenerAdapter.class);
      if (destroyer != null)
        addListener(new DestroyerListenerAdapter(destroyer));
      return this;
    }
docs: Sets the process destroyer to be notified when the process starts and stops.
  <p>
  This methods always removes any other {@link ProcessDestroyer} registered. Use {@link #addDestroyer(ProcessDestroyer)} to keep the existing ones.
  
  @param destroyer helper for destroying all processes on certain event such as VM exit (maybe <code>null</code>).
  
  @return This process executor.