@Override
        public RequestBody convert(T value) throws IOException {
            try {
                byte[] content = JSON.toJSONBytes(value,
                        fastJsonConfig.getSerializeFilters(), fastJsonConfig.getSerializerFeatures());
                return RequestBody.create(MEDIA_TYPE, content);
            } catch (Exception e) {
                throw new IOException("Could not write JSON: " + e.getMessage(), e);
            }
        }
Fastjson for Retrofit Converter Json Factory.
<p>
Compatible fastjson 1.2.x

@author ligboy, wenshao
@author Victor.Zxy
@see Converter.Factory
@since 2.0.2
fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/retrofit/Retrofit2ConverterFactory.java