private static HttpData convertToHttpBody(AggregatedHttpRequest request) throws IOException {
        final ObjectNode body = mapper.createObjectNode();

        try (HttpData content = request.content()) {
            final MediaType contentType;

            @Nullable
            final MediaType requestContentType = request.contentType();
            if (requestContentType != null) {
                contentType = requestContentType;
            } else {
                contentType = MediaType.OCTET_STREAM;
            }

            body.put("content_type", contentType.toString());
            // Jackson converts byte array to base64 string. gRPC transcoding spec also returns base64 string.
            // https://protobuf.dev/programming-guides/proto3/#json
            body.put("data", content.array());

            return HttpData.wrap(mapper.writeValueAsBytes(body));
        }
    }
Returns the {@link Route}s which are supported by this service and the {@code delegate}.
grpc/src/main/java/com/linecorp/armeria/server/grpc/HttpJsonTranscodingService.java