This plugin is a great plugin. But after using it down to find a problem: 
I could not re-enable the stopped EC2 agent, but had to create a new instance.
As for why I need to re-use a stopped EC2 agent, it's because my maven project will download a lot of packages when I build it, and I don't want to repeat the download every time, which will increase my build time.  

If it could reuse the previous instance, then it wouldn't have to re-download these dependencies