code: public RouteBuilder on(String uri) {
          if (!uri.startsWith("/")) {
              this.uri = "/" + uri;
          } else {
              this.uri = uri;
          }
          return this;
      }
docs: Sets the URI (pattern) of the resulting route.
  
  @param uri the uri that can use the route uri pattern, must not be {@literal null}.
  @return the current route builder