This package needs to be brought into the main tree for ant-ivy, see bug #309343. It is available in overlay dmol and can be found in the bgo overlay as well; I'm not certain if they are of good quality so they would have to be checked and reviewed, on a side note they also need to be bumped to version 1.49.
+ 05 Jul 2013; Tom Wijsman <TomWij@gentoo.org> +bcpg-1.49.ebuild, +metadata.xml: + Added new ebuild for dev-java/bcpg, a dependency of =dev-java/ant-ivy-2.3.0.
*** Bug 427636 has been marked as a duplicate of this bug. ***