Not sure if this will help anyone, but I spent half a day trying to solve this issue while integrating Infinispan + Hibernate second-level cache.

Unable to unmarshall 'org.hibernate.cache.internal.BasicCacheKeyImplementation'
as a marshaller is not present in the user or global SerializationContext

Docs say to use application/x-protostream and define marshallers.

But switching to application/x-java-object just worked.
No custom marshallers. No headaches. Just Java doing its things

#java