OneTimeEvent
Event content that can be consumed at most once per wrapper instance.
getContentIfNotHandled atomically marks the instance consumed before returning its content. Competing consumers share that flag; only one can obtain non-null content. This does not acknowledge a completed UI action, retry a cancelled action, or persist across process death. A newly created wrapper has its own consumption flag, even for equal content.
Type Parameters
T
The content type, which may be nullable.