Add support for @JsonIgnoreType for endpoints

[cowtowncoder]

Dropwizard JAX-RS provider seems to add special handling to make anything annotated with @JsonIgnoreType (that is, any endpoint annotated) to be considered "untouchable", that is, not to be processed using Jackson ObjectMapper. This makes sense in that it allows marker for certain kinds of specific classes that Jackson can not and should not handle, instead deferring to some other processing component.

[cowtowncoder]

Another possibility would be to use the new configureOverride mechanism, which allows marking types as ignorable: could just check if return type might be included. Check is efficient and possibly better than annotations.