LPS-33228 Making RepositoryModel a StagedModel too
LPS-33228 StagedModel is already a GroupedModel
LPS-33228 Implementing clone for Liferay* classes in repository model and proxy beans
LPS-33228 clone method for CMIS* repository classes never supposed to be called
LPS-33228 The interface is the contract for the classes - since we have a clone in the contract it would be misleading to return null. Upcoming code portions or customers may be leveraging the clone so we should support it even if it's not called right now.