Mostly resolved as part of the Search 6 proof of concept groundwork.
See in particular the @TypeBridgeMapping and @PropertyBridgeMapping annotation, as well as the AnnotationBridgeBuilder interface.

Followed up by HSEARCH-3135.

I don't think the fact that the custom bridge writes into multiple fields would make a difference. The parameters are per bridge, not per field. After all, parameters are totally up to the user, and so are the resulting fields. They could have a list of annotations, one for each resulting field, if they wanted to:

On the other hand, some custom bridges may write to multiple fields without needing separate parameters for each field.

I'm also a bit concerned with requiring people to write their own annotations. It's really simple, but not very common, so it might put some users off. We could offer some kind of "simpler" annotation, similar to what we had before 6.0, to make it possible to opt out:

That would definitely be less powerful, though. And it could confuse users to have two ways of doing exactly the same thing. In the end, having a detailed example in the documentation might be a better solution.

Ok that looks nice indeed. The only drawback I see is that I'm not sure how familiar people are with creating their own annotations, but it's very minor.

Would be interesting to explore a similarly declarative way for those bridges which need to write into multiple fields? After all what we need is for people to declare this upfront.

I think it's about applying custom bridge using custom annotations, a bit like what is mentioned in HSEARCH-18. It would be close to how custom validation works in Hibernate Validator.

I think it would be a very, very nice way to implement the concept of "complex field bridge" we talked about (bridges that aren't just simple functions). We could introduce something like that in Hibernate Search 6:

MyCustomBridge.java

MyEntity.java

MyCustomBridgeImpl.java

Time to undust this one. Could you elaborate, especially now that we're thinking of making these pluggable?