I think the project.build.sourceEncoding property is not honored in
Wheezy (older Maven plugins). Try disabling the tests by turning
maven.test.skip to true in debian/maven.properties.
Changing this property according to the value of DEB_BUILD_OPTIONS is a
good improvement idea for maven-debian-helper.
This is the maintainer address of Debian's Java team
debian-j...@lists.debian.org for discussions and questions.