private static boolean validateAcceptHeaders(HttpRequest req, SerializationFormat serializationFormat) {
        // If accept header is present, make sure it is sane. Currently, we do not support accept
        // headers with a different format than the content type header.
        final List<MediaType> acceptTypes = req.headers().accept();
        return acceptTypes.isEmpty() || serializationFormat.mediaTypes().match(acceptTypes) != null;
    }
Returns the default {@link SerializationFormat} of this service.
thrift/thrift0.13/src/main/java/com/linecorp/armeria/server/thrift/THttpService.java