Yesterday I was wondering if Microsoft support middleware packages for Java to allow the typical resource provider actions in an access_token or id_tokens, similarly to what the OWIN NuGet packages do or the PassportJS libraries for NodeJS. These last two libraries act as middlewares intercepting the HTTP requests. They allow to, programmatically, parse the Authorization headers to extract Bearer tokens, validate the tokens, extract claims from the tokens etc, etc.
The libraries I had found so far, and that I was familiar with, were the MSAL set of libaries and the ADAL set of libraries. These are client side libraries, meant for applications acting or APIs acting as OAuth2 Clients (not as Resource Providers)
Microsoft does not maintain a Java middleware library similar to OWIN or Passport. The development team is using Spring and will use Azure Active Directory as the Identity Provider, they could use Spring Boot Starter for AAD: https://github.com/microsoft/azure-spring-boot/tree/master/azure-spring-boot-starters/azure-active-directory-spring-boot-starter
Spring Boot is a wrapper of Spring Framework libraries packaged with preconfigured components.
They can also work with AAD and Spring Security, but there aren’t many articles out there related to that framework and how to use it when AAD is the IdP providing JWT tokens except for this one:
Article and related links: https://azure.microsoft.com/en-us/blog/spring-security-azure-ad/
There is also this old blog post with some sample code(using spring framework security, however the example is for illustration purposes only, and uses an access_token issued for a SPA client application in order to request access to an API, which is not exaclty the case of the application we’re trying to modernize (multi-page JSP web application)
https://dev.to/azure/using-spring-security-with-azure-active-directory-mga