Please recommend open-source Java web applications that exemplify the most common enterprise software architectures like:
What I'm looking for is an end-user enterprise web application like Trello, Slack, hotel booking, warehouse tracking, online courses (stuff that is used directly by typical business users like sales managers, warehouse staff, tutors etc).
The ideal project would be an clean example of a specific architecture using Java, OOP and popular frameworks like Spring and Hibernate (not a crazy hybrid of 5 architecture styles and 3 programming paradigms) in the form of an end-user web app (not an IDE, tool, framework or middleware). **The main idea is a good educational effect via unambiguity in the choice of architecture style and paradigm, and clarity and structure of the project.**
I believe these are the kinds of projects a typical entry-level and mid-level Java developer will be involved in professionally, so I think a nice list of these will greatly benefit this vast category of developers and help them transition from writing code to thinking like an architect.
P.S. Yes, I've done a lot of googling and most projects offered by open-source communities are coding tools, frameworks or middleware like JUnit, Hibernate or Elasticsearch.