That's the one. I learnt it by pair-programming (which is great but not necessarily replicable). From a quick search, their userguide has a fairly light introduction to why: https://nightlies.apache.org/wicket/guide/9.x/single.html#_w... . And the book https://livebook.manning.com/book/wicket-in-action/chapter-2... has a more detailed explanation of the what.