Stream created by a StreamProvider.
The stream obtained is not strictly identical to the stream created. Instead, this stream is always a broadcast stream.
The stream obtained may change over time, if the StreamProvider is re-evaluated, such as when it is using Ref.watch and the provider listened changes, or on ProviderContainer.refresh.
If the StreamProvider was overridden using
a stream will be generated and manipulated based on the AsyncValue used.
AlwaysAliveProviderBase<Stream<State>> get stream => AsyncValueAsStreamProvider(this, from: from, argument: argument);