I haven't been in the java ecosystem in a while, but when I was using Maven you could just download the portable version and run it, and towards the tail end yo

I haven't been in the java ecosystem in a while, but when I was using Maven you could just download the portable version and run it, and towards the tail end you could just include a simple mvn build shim that would pull down the correct version of maven and run it in a portable way (I think this was an idea borrowed from Gradle). Maven itself, afterall, was nothing more than a java application (as was Ant before it).