Several other libraries are embedding Hibernate Search to bridge custom values into Lucene indexes but so far we're expecting a 1:1 match between class definitions and different indexed "types".

Some indexed "types" should be representable by the same valueholder java type but having attributes defined at bootstrap (for example from a protobuf schema).

A common requirement is to have the "user type" defined by a name rather than a class; that implies then that we need to be able to have queries targeting (narrowing down) to this specific type based on the string name rather than the Java class definition.