Dave Syer opened SPR-16529 and commented

GsonHttpMessageConverter cannot be used in an SseEmitter (unlike MappingJackson2HttpMessageConverter) because it closes the output stream after every element, committing the HTTP response and shutting it down in the servlet container. To verify this you only need to build an app with Jackson and an SseEmitter, then switch to Gson and see it break (only the first event is emitted).

Affects: 4.3.14

Issue Links:

• GSON converter only serialises fields of controller method return type, ignoring subclass fields of response object [SPR-16461] #21006 GSON converter only serialises fields of controller method return type, ignoring subclass fields of response object

Backported to: 4.3.15