The table Hibernate Search Deprecated Interfaces in chapter 5.8. Hibernate Search Changes of the Migration Guide has this text:

This interface will be moved and should be considered non-public API [HSEARCH-1915].

The "[HSEARCH-1915]" bit is probably supposed to link to https://hibernate.atlassian.net/browse/HSEARCH-1915, but it doesn't. And it should be a part of proper sentence, something like "See HSEARCH-1915 for more".

Alternatively, the "[HSEARCH-1915]" bit is not supposed to be there at all. Don't know.