@Streaming(false)
        @Get("/serverSentEventMono")
        @ResponseConverter(ServerSentEventResponseConverterFunction.class)
        public Mono<ServerSentEvent> serverSentEventMono() {
            return Mono.just(ServerSentEvent.ofData("serverSentEventMono"));
        }
A mock service for testing {@link ServerSentEventResponseConverterFunction}.
core/src/test/java/com/linecorp/armeria/internal/server/annotation/ResponseStreamingTest.java