This isn't an accusation, but was this comment written with AI? There's a glaring logical error here which I think a human would catch easily, but an LLM (which is just a natural language generator, not a logic processor) could possibly overlook.
Specifically, your arguments don't really make a lot of sense. They're also not targeted at my claim. It reads more like a defense of JPlus. To which I want to clarify, I merely took issue with the specific claim I quoted, I wasn't trying to say there's no point to JPlus. There's no need to defend JPlus in general. So I'm going to dismiss runtime behaviors since that has nothing to do with the syntax.
Groovy introduces dynamic typing
Java has dynamic typing already. Groovy introduced it first, but it's not a Groovy exclusive feature anymore. It's also optional.
additional syntax
There being additional syntax doesn't matter if it's optional. We're talking here about whether Java code works in Groovy/JPlus, and it does. Not the other way around. At least that's what I understood.
JPlus also adds the nullsafe and elvis operators, so it also adds additional syntax and JPlus code won't work when compiled with Java directly.
Groovy is highly compatible with Java and most Java code runs in Groovy without changes. However, it’s not 100% identical.
JPlus also doesn't guarantee being 100% identical. It says "mostly" the same.
Basically, none of the arguments really compare the two in the context given. The runtime behavior is the only real difference listed here, but that's irrelevant in the context of them being supersets.