code: public static void addCustomDeviceData(final String key, final String value) {
  		dispatchConversationTask(new ConversationDispatchTask() {
  			@Override
  			protected boolean execute(Conversation conversation) {
  				conversation.getDevice().getCustomData().put(key, trim(value));
  				return true;
  			}
  		}, "add custom device data");
  	}
docs: Add a custom data String to the Device. Custom data will be sent to the server, is displayed
  in the Conversation view, and can be used in Interaction targeting.  Calls to this method are
  idempotent.
  
  @param key   The key to store the data under.
  @param value A String value.