@Streaming(false)
        @Get("/httpDataFuture")
        public CompletableFuture<HttpData> httpDataFuture() {
            return UnmodifiableFuture.completedFuture(HttpData.ofUtf8("httpDataFuture"));
        }
A mock service for testing {@link ByteArrayResponseConverterFunction}.
core/src/test/java/com/linecorp/armeria/internal/server/annotation/ResponseStreamingTest.java