stateMiddleware function
Builds the middleware that puts state on every request below a group.
Returns null when a group attached nothing, so groups without state add
no layer at all.
Implementation
Middleware? stateMiddleware(Map<String, Object> state) {
if (state.isEmpty) return null;
final snapshot = Map<String, Object>.unmodifiable(state);
return (Handler inner) {
return (Request request) => inner(request.change(context: snapshot));
};
}