I believe this may be the cause of the sporadic ClassCastExceptions being thrown:

https://github.com/forge/furnace-cdi/blob/master/impl/src/main/java/org/jboss/forge/furnace/container/cdi/impl/ServiceRegistryImpl.java#L292

Using just the hashCode is not a good option. Using the class name would be more appropriate. Needs to be reviewed .