Version used: 2.8.0-alpha01

In the latest alpha version, there's now the ability to retrieve Closeable objects previously added to a ViewModel, which is great.

I did notice though that the (internal) setTagIfAbsent method has been removed and ViewModel.viewModelScope (which previously used setTagIfAbsent) now uses getCloseable and addCloseable separately.

I'm thinking this might be problematic as the operation appears to no longer be atomic? E.g. the viewModelScope may be saved and then a new one saved again, which will overwrite the first one in the Map and hence whatever job(s) it had launched would no longer be cancelled with the ViewModel.

I assume that the issue of concurrency is important here given the synchronized blocks, and that other scopes seem to have pretty stringent measures (e.g. Lifecycle.coroutineScope). Maybe Collections.synchronizedMap and Collections.synchronizedSet could also be helpful?

Aside from concurrency issues, the new addCloseable method doesn't actually take into consideration whether a Closeable has already been added with the same key, so there is plenty of potential for accidental overwrites, which would likely cause leaks when the the original overwritten Closeable disappears from the Map.

Regardless of the above, it would be nice to have something along the lines of putIfAbsent and/or computeIfAbsent in the public ViewModel API as part of this new feature, alongside the standard addCloseable and getCloseable.