Hi all, I had to make a minor change to Equivalence<T> to make things work. I've made Equivalence<T> extend Serializable. The reason for doing that is EquivalentCHMv8, and any other equivalent collections are Serializable, so anything they reference must be either Serializable or transient, and I don't want to force an Infinispan marshaller on these classes. I've noticed this because some lucene code stores instances of Infinispan's ConcurrentHashSet into the cache (represents File list AFAIK, @Sanne?). I could have worked around this by either providing an Externalizer for AnyEquivalence, but this would only have worked for situations were these equivalent collections were stored in a cache. Anyone could potentially create an instance of our equivalent concurrent collections and just try to serialise it. If you really wanna make the most out of it, you can always provide an Externalizer, just like it's been since we added Externalizers, but given that I see Equivalence instances as mostly stateless, just making it extend Serializable is quite simple solution. Cheers, On Apr 25, 2013, at 7:35 PM, Galder Zamarreño <galder(a)redhat.com&gt; wrote: -- Galder Zamarreño galder(a)redhat.com twitter.com/galderz Project Lead, Escalante http://escalante.io Engineer, Infinispan http://infinispan.org