The filters ChainedFilter, DistanceFilter and SpatialHashFilter does not have their own implementations of the #equals() and #hashCode() methods. A filter may be used as a key for the Lucene's QueryCache and this cache requires that all queries (a filter is a query) must provide proper implementations of the #equals() and #hashCode() methods. The absence of the implementations for this methods may lead to incorrect results of a query execution.

Btw. I think Hibernate Search should allow to configure different QueryCache and QueryCachingPolicy.