code: public static EventBus getDefault() {
          EventBus instance = defaultInstance;
          if (instance == null) {
              synchronized (EventBus.class) {
                  instance = EventBus.defaultInstance;
                  if (instance == null) {
                      instance = EventBus.defaultInstance = new EventBus();
                  }
              }
          }
          return instance;
      }
docs: Convenience singleton for apps using a process-wide EventBus instance.