https://docs.spring.io/spring-framework/docs/3.0.x/spring-framework-reference/html/overview.html

https://spring.io/quickstart

https://www.geeksforgeeks.org/devops/building-a-3-tier-web-application-architecture-with-aws-cli/

https://microservices.io/patterns/microservices.html

https://www.geeksforgeeks.org/system-design/hexagonal-architecture-system-design/

https://www.baeldung.com/spring-tutorial

https://www.digitalocean.com/community/tutorials/spring-tutorial-spring-core-tutorial

================================================== java: error: release version 5 not supported Module demo SDK 25 does not support source version 1.5. Possible solutions: - Downgrade Project SDK in settings to 1.5 or compatible. Open project settings. - Upgrade language version in Maven build file to 25

Your IDE might be fighting your build config.

Check module setting of project:

Project SDK → set to 17 or 21 Project language level → same version Module SDK → don’t let it drift Maven importer JDK → same again ==================================================

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