If a marshaller class is configured, the cache should reuse marshaller instances via MarshallerRegistry.
If a marshaller instance is configured, the cache should use the actual instance.

Another option would be to always reuse instances:

• Cache configuration could reference a media type or a marshaller class, but not a marshaller instance.
• Marshaller instances would be registered directly with the RemoteCacheManager and go into MarshallerRegistry.
• Advanced users that need to use different marshaller instance for the same media type (e.g. 2 ProtoStreamMarshallers with different schemas) would have to use `RemoteCache.withDataFormat()`