code: public static synchronized void sse(String url, BiConsumer<ServerSentEventConnection, String> connectionCallback) {
          checkStarted();
          instance().endpoints.add(HandlerUtil.sse(url, connectionCallback));
      }
docs: Define a Server sent events endpoint with a specified handler. Supports path variables
  Data can be broadcast to this endpoint by using {@link io.joshworks.snappy.sse.SseBroadcaster}
  
  @param url                The relative URL to be map this endpoint.
  @param connectionCallback Endpoint handler.