Warning never assigned on [SerializeReference] using interface

[SwingWren]

When using [SerializeReference] attribute and an Interface you get a never assigned warning

[igor-elovikov]

It also affects collections and with collections rider always suggesting to convert it to readonly (which breaks serialization) https://youtrack.jetbrains.com/issue/RIDER-94348/SerializeReference-and-generic-collection-holding-interface

Currently it's very annoying to use [SerializeReference] with any form of interface which is a very valid use case.