2. This means you can’t have more than one version active in Eclipse at a time.
Yes.
3. New versions of Eclipse will ship with the latest released lsp4e
Yes.
4. The older code stream will thus be for users of older eclipse wishing to upgrade LSP4e but not wanting to take the latest eclipse.
0.20.x would befor user who want to stick to Java 11 version, not necessarily older Eclipse.
Is that about right? I’m also slightly hazy on exactly how it is decided, for plugins that ship with Eclipse, which versions will go into the latest Eclipse and how any dependency conflicts are to be resolved, and indeed which version of Java Eclipse should require. I’m sure there are policy documents or a release plan somewhere but I never seem to have found clear guidance from poking around on the Eclipse website.
FWIW we have our own version of LSP4e (built with a different name and extension point namespace to avoid clashing) but are trying to work towards using released LSP4e directly. Unfortunately we need to support a customer who has great difficulty in upgrading Eclipse due to some custom legacy plugins they need to keep working, so I have been building lsp4e with a few custom patches to keep it Java 8 compatible. There wasn’t actually that much code in LSP4e that required patching but the Java 17 changes, although mostly syntactic sugar, are a lot more extensive.
I would personally recommend you to start billing more and more to support Java 8, and/or to sell to that customer some services to allow them to move to Java 17 and stop being a burden for themselves and their service providers :P
However, if you're willing to keep Java 8 support for your fork from master, you just need to add to your forked LSP4E the revert commits for the few ones that are about Java 17 on master. From here, it wouldn't be too different as now; but indeed, as Java 17 has lots of very good syntactic addition (that are not only sugar as they actually have a good effect on code correctness), it's very likely that the new constructs get more and more popular, and the amount of work you have to do to Java-8-ify newer code becomes higher and higher.
HTH
