In my (Vaadin 24.4.10) application some custom Vaadin Components implement onDetach and release/close ressources that have been initialized in the constructor of those components.
This is to release memory early, e.g. when the user switches from one form to another form.
After onDetach everything that happened in the constructor is rolled back and these components have only a very small memory usage.

Unfortunately there is a situation where this leads to a problem:
When Vaadin starts resynchronizing UI by client’s request, then ServerRpcHandler.handleRpc calls ui.getInternals().getStateTree().prepareForResync(). And this leads to a call of onDetach and after that to a call of onAttach.

So when a resynchronizing happens, then my custom components have cleaned up themselves and are more or less unusable without re-calling the constructor.

One approach would be to move everything from the constructor to the onAttach method.

Another approach could be that the onDetach implementation recognizes the resync and does not clean up everything (if anything at all).
I think that this approach is a lot less work and risk in my case than moving everything from the constructor to the onAttach method, so I’d like to follow this approach.

The question / problem is: How can the onDetach method recognize that it’s in the resync? StateNode.prepareForResync() does not set a flag before it fires the detach listeners.

(A (temporary) workaround would be that I search in the StackTrace for the method prepareForResynch. This is unsafe because in the future the method could be renamed. So I’m looking for a future-safe way of recognizing whether resynchronization is active in the onDetach call.)