dev-java/stringtemplate-4.0.5 was released on 2011-07-18.
Stringtemplate 4.0.6 was released on 26.09.2012. The complete changelog for 4x is here: https://github.com/antlr/stringtemplate4/blob/master/CHANGES.txt
BTW, 4.x is not compatible with 3.x: http://www.antlr.org/wiki/display/ST4/Differences+between+v3+and+v4
Version 4.0.7 was released on 4th of Jan 2013
Not sure which antlr version we exactly need, but it is clear we need a bump; added two bugs to "depends on" field to reflect this.
dev-java/stringtemplate-4.0.8 was released on 2014-03-25.
4.0.8 is now in the tree.