# ProblemDetail.forStatus(404).getType(), evaluated in jshell against each spring-web jar

spring-web-6.2.19.jar  ->  getType() = about:blank
spring-web-7.0.9.jar  ->  getType() = null

# Both versions' ProblemDetailJacksonMixin carry @JsonInclude(NON_EMPTY), so 6.2 rendered
# "type":"about:blank" and 7.0 omits the member. As rendered by this application (7.0.9):
$ curl /no-such-thing
{"detail":"No static resource no-such-thing.","instance":"/no-such-thing","status":404,"title":"Not Found"}
