Currently we have our own custom copy of CachingWrapperQuery/CachingWrapperFilter, and we handle DocIdSet caching that way.
CachingWrapperQuery and CachingWrapperFilter have been deprecated and will be removed in a future version of Lucene. We'll probably want to switch over to the new caching method, which is org.apache.lucene.search.QueryCache.

Note: it might not be possible, because we expose FilterCachingStrategy as an API, and this API may not be appropriate for org.apache.lucene.search.QueryCache.