MappingJackson2HttpMessageConverter character encoding not propagated to the response #36046
Description
We add a Jackson message converter to our content negotiation manager, like this:
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" c:objectMapper-ref="objectMapper" p:supportedMediaTypes="application/json" />Recently we had to remove all references to APPLICATION_JSON_UTF8_VALUE (aka "application/json;charset=UTF-8") because it is removed in Spring 7.
When an endpoint has produces metadata without a charset parameter, like "application/json", the MappingJackson2HttpMessageConverter falls back to this method to determine the character encoding of the response:
/**
* Determine the JSON encoding to use for the given content type.
* @param contentType the media type as requested by the caller
* @return the JSON encoding to use (never {@code null})
*/
protected JsonEncoding getJsonEncoding(@Nullable MediaType contentType) {
if (contentType != null && contentType.getCharset() != null) {
Charset charset = contentType.getCharset();
JsonEncoding encoding = ENCODINGS.get(charset.name());
if (encoding != null) {
return encoding;
}
}
return JsonEncoding.UTF8;
}The default (fallthrough) value is UTF-8. However, when this path is taken, no charset parameter is added to the Content-Type response header. Thus the caller may assume the HTTP default encoding of ISO-8859-1.
Workaround: set p:defaultCharset="UTF-8" on the message converter.
Is it possible to always add a charset parameter to the Content-Type response header within AbstractJackson2HttpMessageConverter?
This is Spring 6.2.13