onRequest method
Called when the request is about to be sent.
Implementation
@override
void onRequest(RequestOptions options, RequestInterceptorHandler handler) {
if (!enabled || (filter != null && !filter!(options))) {
handler.next(options);
return;
}
final requestTime = DateTime.now();
// Store timing info in extras for response/error handlers
options.extra[_kRequestTimeKey] = requestTime.millisecondsSinceEpoch;
handler.next(options);
}