private static void respond(SerializationFormat serializationFormat,
                                HttpData content, CompletableFuture<HttpResponse> res) {
        res.complete(HttpResponse.of(HttpStatus.OK, serializationFormat.mediaType(), content));
    }
Returns the default {@link SerializationFormat} of this service.
thrift/thrift0.13/src/main/java/com/linecorp/armeria/server/thrift/THttpService.java