[infinispan-dev] Deprecating the @ProvidedId annotation w/o a replacement in place

I'm deprecating the `org.hibernate.search.annotations.ProvidedId` annotation in Hibernate Search. This was originally introduced when Infinispan Query was first designed as a way to mark the Infinispan value object as "something which doesn't contain the id", since in the key/value store world the key can usually not be extracted from the value (which is a difference from the Hibernate ORM world). In early days, this meant that all indexed objects in Infinispan had to be marked with this, but we quickly fixed this oddness by simply assuming that - when using Hibernate Search to index Infinispan objects - we might as well consider them all annotated with @ProvidedId implicitly. So the main reason for this annotation to exist is long gone, but its role evolved beyond that. This annotation was also enabling a couple more features: A] allow the user to pick the index field name used to store the IDs B] allow to bind a custom FieldBridge to the key type # A: customizing the field name from "providedId" I don't think this is actually very useful. It is complex to handle when different types might want to override this, and the rules at which this is valid across inherited types. I'm proposing we take this "mapping flexibility" away with no replacement. # B: custom FieldBridge for indexing of Infinispan keys Infinispan already has the notion of Transformers, which is similar but not quite the same. The differences are confusing, and neither of them actually makes it very clear how to e.g. search by some attribute of the key type. Clearly there's need for a better approach to deal with keys, and @ProvidedId doesn't fit well in such plans. For now I plan to mark @ProvidedId as deprecated; although I won't remove it yet until we have an alternative in place to better deal with keys. However, I'm unable to properly document what its replacement should be until we fleshed out the alternative. I'd like to proceed with the deprecation even without having the replacement already as I suspect what we had so far for indexing keys was not good enough anyway. Deprecating it is rather urgent as it turns out it's all quite confusing when this annotation should be used. Thanks, Sanne