The base interface for the virtualization system. An Epic maintained version can be found in the Virtualization module. To implement your own, simply derived from this interface and then use the UE_REGISTER_VIRTUALIZATION_SYSTEM macro in the cpp to register it as an option. You can then set the config file option [Core.ContentVirtualization]SystemName=FooBar, where FooBar should be the SystemName parameter you used when registering with the macro.