activeCopy

The transfer that last held this connection in copy mode, live or spent.

On the stream rather than on the CopyManager or Session that started it, because it outlives every one of them: a manager belongs to one session, and several sessions can be opened over one connection in turn, each with a manager of its own.

Set by the operations under lock and never cleared - CopyOperation.isActive is the authority on whether it still refers to anything live.