fetch method
Waiting to get the RemoteConfig value. And when the wait is complete, the callback function will be executed.
Implementation
Future<void> fetch(final int timeoutMillisecs, _ReproCallback callback) async {
var args = [timeoutMillisecs];
var cleanUpFunc = await Repro._startListening(
methodName: 'startListening_remoteConfig_fetch',
callback: callback,
arguments: args,
resultTypeName: 'FetchStatus');
await Future.delayed(Duration(milliseconds: timeoutMillisecs + 1000));
cleanUpFunc();
}