This is a Spring Boot REST API that can be built and deployed to Azure App Services and/or Azure Kubernetes Services (AKS). The REST API requires that you passs an access token that you must aquire from Azure AD to enable an API to be secured with your tenants identities.
You can find references on how to use Spring Boot together with Azure AD here https://github.com/Microsoft/azure-spring-boot
There exists an Angular.js sample in the github repo that uses a REST API backend which is basis for this REST API.