public GraphqlServiceBuilder webSocketServiceCustomizer(
            Consumer<WebSocketServiceBuilder> webSocketServiceCustomizer) {
        requireNonNull(webSocketServiceCustomizer, "webSocketServiceCustomizer");
        this.webSocketServiceCustomizer = webSocketServiceCustomizer;
        return this;
    }
Sets an optional {@link WebSocketServiceBuilder} customizer.
graphql/src/main/java/com/linecorp/armeria/server/graphql/GraphqlServiceBuilder.java