Make AbstractSmartHttpMessageConverter more extensible, allowing for custom hints

** Enhancements requests **
My use case would be to customize the Json Serialization process for some specific RestController method, and more specifically when serializing a list of objects I want to ignore Jackson identity information to and let Spring/Jackson serialize a small referenced object corresponding to an entity multiple times in order to allow the client to display the information more easily as a table.

I think the hints mechanism would be well suited for something more generic. As per my understanding of spring http I can see the following implementation paths,

• AbstractJacksonHttpMessageConverter is slightly refactored to offer a method createMapper or customizeMapper that could be overridden to support handling of custom hints. Then we could provide our own converter!
• A new general Hint CustomizeMapper or an Hint Mixins could be implemented in internalWrite/internalRead besides Views and Filters handling. The Hint when present would steer the creation of new Mapper using Jackson efficient "rebuild", customize, "build" or "rebuild", addMixins, "build" pattern.

I'd happily discuss it here and / or submit a pull request if Spring maintainers support the idea.

Thanks you all at Spring for your great work ;)

Start by reading AbstractSmartHttpMessageConverter and AbstractJacksonHttpMessageConverter, especially the internalWrite/internalRead paths that handle views and filters. Compare the proposed createMapper/customizeMapper and custom-hint approaches, then determine the supported extension point and its expected behavior for controller-specific Jackson serialization hints.