baeldung
https://www.baeldung.com/spring-boot-keycloak
    https://github.com/eugenp/tutorials/tree/master/spring-boot-modules/spring-boot-keycloak
https://www.baeldung.com/spring-boot-keycloak-integration-testing
    with testcontainers
https://www.baeldung.com/java-keycloak-custom-user-providers
https://www.baeldung.com/keycloak-embedded-in-spring-boot-app
    https://github.com/Baeldung/spring-security-oauth/tree/master/oauth-rest/oauth-authorization-server
https://www.baeldung.com/postman-keycloak-endpoints
2025
https://mydeveloperplanet.com/2025/06/11/secure-your-spring-boot-apps-using-keycloak-and-oidc/
https://mydeveloperplanet.com/2025/05/28/setup-openid-connect-with-keycloak-a-step-by-step-guide/
    https://github.com/mydeveloperplanet/myspringsecurityplanet
https://habr.com/ru/companies/oleg-bunin/articles/936338/
2023
https://medium.com/@buffetbenjamin/keycloak-essentials-openid-connect-c7fa87d3129d
    Realm - Identity Provider
    User - End User
    Client - Relying Party
        confidential
        public
    Scope - collection of resources to access
    Flow
        Authorization Flow
2023
https://habr.com/ru/companies/axenix/articles/780422/
    !!! a lot of kc info
https://habr.com/ru/articles/716232/
    ! good
https://habr.com/ru/articles/772010/
    ! intro
    https://github.com/mgalaktionov/keycloak-demo-2
https://habr.com/ru/companies/otus/articles/733404/
    ! use kc-based roles insetead of spring-security ones
https://habr.com/ru/articles/546428/
    ! misc stuff, incl web and localization
https://habr.com/ru/companies/kaspersky/articles/756812/
    ! otp, rbac
https://habr.com/ru/companies/nixys/articles/752994/
    ! ldap
https://habr.com/ru/post/724738/
    ! spring-securit kc-relates stuff, refresh-token filter etc
2021
https://habr.com/ru/companies/reksoft/articles/552346/
    ! + spring security
2020
https://habr.com/ru/companies/southbridge/articles/511380/
    HA
2019
https://developer.okta.com/blog/2019/10/21/illustrated-guide-to-oauth-and-oidc
    https://www.youtube.com/watch?v=t18YB3xDfXI