Class ProxyPropCnrImpl

Implementation of the proxy from a source container to a target container. The target container is allowed to set property values that is transported back to the source (as an option).

The proxy property does not transport private properties or properties with null values: these are left out of the target, and a property that stops qualifying is removed from it. A property carrying an error IS transported, and its error travels with the clone; an error is not a reason to leave a property out.

Echo suppression: every mirrored operation marks the property it is about to touch in the other tree on the CURRENT THREAD, so that the event the operation fires there is not mirrored back. The slot is saved and restored around the operation, so a listener cascade that triggers a second proxy operation inside the first cannot clear the outer operation's slot, and a thread never sees the slot of another thread.