onRequest method
Called when the request is about to be sent.
Implementation
@override
Future<void> onRequest(
dio.RequestOptions options,
dio.RequestInterceptorHandler handler,
) async {
final event = NetworkEventLog.requestNow(
request: options.toRequest(),
error: null,
response: null,
);
_requests[options] = event;
eventList.add(event);
handler.next(options);
}