code: protected EventBase<T> setRequiresResult(boolean value) {
          if (requiresResult == value) {
              return this;
          }
          if (value) {
              openCount.incrementAndGet();
              requiresResult = true;
          } else {
              requiresResult = false;
              decrementOpen();
          }
          return this;
      }
docs: See {@link Event#setRequiresResult(boolean)}.