@Produces(MediaTypeNames.PLAIN_TEXT)
        @Streaming(false)
        @Get("/stringTextPublisher")
        public Publisher<String> stringTextPublisher() {
            return StreamMessage.of("stringTextPublisher");
        }
A mock service for testing {@link ServerSentEventResponseConverterFunction}.
core/src/test/java/com/linecorp/armeria/internal/server/annotation/ResponseStreamingTest.java