Please see https://developer.jboss.org/thread/258545 for details. The key issue is:

The ClassCastException happens when trying to iterator the cache:
06:54:47,057 ERROR [org.jboss.as.ejb3.invocation] (http-localhost/127.0.0.1:8680-1) JBAS014134: EJB Invocation failed on component PublishManagerLocalBean for method public abstract java.util.Set com.test.PublishManager.getChannels(): javax.ejb.EJBException: java.lang.ClassCastException: org.infinispan.marshall.core.MarshalledValue cannot be cast to com.test.Channel

The problem is: I store only one entry into the cache. But afterwards when iterating the cache, 2 entries are returned. One entry is with type Channel which looks correct, but there is another entry with type MarshalledValue.

After a few investigation, we see this issue only happens when the 1. cache is persistent and 2. storeAsBinary is enabled.