Dear Benda,

although I am not a Gentoo developer myself, 
I would be interested in joining effort to get Maven packages
working in Gentoo. It is obvious that some kind of automation 
would be beneficial for Gentoo - to get more recent up-to-date
package versions somehow available in the Gentoo tree.

Maybe the page in the Debian Wiki [1] might also be interesting.

[1] https://wiki.debian.org/Java/MavenBuilder

Best wishes,

Harald.