code: public FwWebDirection assistWebDirection() {
          if (webDirection != null) {
              return webDirection;
          }
          synchronized (this) {
              if (webDirection != null) {
                  return webDirection;
              }
              final FwWebDirection direction = createWebDirection();
              prepareWebDirection(direction);
              webDirection = direction;
          }
          return webDirection;
      }
docs: =====