Java support

[zugaldia]

I don't see Java listed in the plugin documentation as one of the supported languages for deployment. If it isn't supported, we could use this ticket to track potential Java support for the plugin. If it's supported, we can simply use this ticket to track a documentation update.

[jprobinson]

Howdy @zugaldia!

Java support was not included with the initial release as we haven't had a use case yet and it required a little more software to be installed than the other languages.

Looking at the docs for Java and App Engine, I think we'd need to also get at least Java 7 and Maven installed in our Docker image. From there, we'd likely need to add support for a new command to kick things off via Maven.

Definitely interested in adding support if you and/or others want to collaborate.