Add new Archetype for vaadin 7.5.9 with Java 8

I have added a new archetype for new vaadin release 7.5.9 .
Now my pom looks like:


[/size]How can set the pom to use java 1.8 instead of 1.7? I know i can just change the value in pom, but is there a way to set
this as a fixed value, so that after creating a new vaadin maven project, the values for source and target versions are 1.8 by default?