public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType,
                                  Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest request,
                                  ServerHttpResponse response) {
        MappingFastJsonValue container = getOrCreateContainer(body);
        beforeBodyWriteInternal(container, selectedContentType, returnType, request, response);
        return container;
    }
Default JSONP query param names: callback/jsonp
src/main/java/com/alibaba/fastjson/support/spring/FastJsonpResponseBodyAdvice.java