发生在 Spring Boot 使用的旧 *.xml 配置的一部分中，我们有 <mvc:annotation-driven/>代码>.

It occurred that in part of our old *.xml config which was used by Spring Boot we had <mvc:annotation-driven/>.

这导致第二次使用没有 GsonHttpMessageConverter 的默认转换器创建 RequestMappingHandlerAdapter.

It was causing creation of RequestMappingHandlerAdapter 2nd time with default converters without GsonHttpMessageConverter.