code: public Route to(Controller controller, String method) {
          Preconditions.checkNotNull(controller);
          Preconditions.checkNotNull(method);
          this.controller = controller;
          try {
              this.controllerMethod = verifyThatControllerAndMethodExists(controller.getClass(),
                      method);
          } catch (Exception e) {
              throw new IllegalArgumentException(ERROR_CTRL + method + ERROR_IN + controller
                      .getClass() + "`, or the method is invalid", e);
          }
          return _build();
      }
docs: Sets the targeted action method of the resulting route.
  
  @param controller the controller object, must not be {@literal null}.
  @param method     the method name, must not be {@literal null}.
  @return the current route builder