cancel or stop a SSE endpoint connection

func handleUnknownEventPath(w http.ResponseWriter) {  w.WriteHeader(http.StatusMethodNotAllowed)  fmt.Fprintln(w, "Unknown method")  w.(http.Flusher).Flush()}

immediately after calling this method return statement is used. but the connection is not stopping it still dangling open. but the status code is delivered, but the connection is still open. How to close the connection from the server side, like it happen to the normal GET requests.