Secure java application on Foundry and call it from external tool

Hi experts,

I'm developing a java servlet in SCP Foundry using the SAP Web IDE Full-Stack. I need to secure the servlet avoiding to access it without specific authorizations. I've followed this tutorial (concepts are explained very well):

Secure Your Application on SAP Cloud Platform Cloud Foundry

It works great and after prompted the right credentials, managed by Application Router, all the authorizations are correctly applied and the servlet is executed. Now I want to call this kind of servlet from an external tool (for example Postman). How to do it?

I don't know if this is the right way because the App Router works very well when there is a browser (and so a real user on the other side...) but I don't understand how to reach the same result calling it from external. I think this is not the real scope of App Router because it always need a user and so how is possibile to protect a java application and call it from external tool?

Thanks in advance

Luca