code: public QueueSettings merge(QueueSettings other) {
      if (onBackend == null && onModule == null) {
        onBackend = other.getOnBackend();
      }
      if (onModule == null && onBackend == null) {
        onModule = other.getOnModule();
        moduleVersion = other.getModuleVersion();
      }
      if (onQueue == null) {
        onQueue = other.getOnQueue();
      }
      return this;
    }
docs: Merge will override any {@code null} setting with a matching setting from {@code other}.
  Note, delay value is not being merged.