onRequest method
Called when the request is about to be sent.
Implementation
@override
void onRequest(
RequestOptions options,
RequestInterceptorHandler handler,
) async {
/// If token exists, add it to the request headers.
if (token != null && token.toString().isNotEmpty) {
options.headers['Authorization'] = 'Bearer $token';
}
/// Continue with the request.
handler.next(options);
}