I have a architecture consisted of mobile application(flutter), api 1, and api 2. The api 2 is secured by identity server 4. My scenario is mobile application need to authenticate user via azure ad directory. After getting the azure ad token in mobile application, i have no idea how to exchange it with identity server 4 token that is currently used to secure my api 2. My current workaround implementation is done by using flutter appauth to open up the identity server 4 login screen which will redirect user to azure ad login. Once user login, the identity server 4 will return the access token that can be used to access api 2 to my mobile application. In general, my mobile application will pass the token to api 1 and api 1 to api 2 during request. Just wonder is this architecture has any issue? Because recently i came across the Extension grant in identity server 4 from link