NMUs are welcome
Use something like the script below to update from Git
#!/bin/bash
VERSION=6.3~svn680
echo "*.jar export-ignore" > .gitattributes
git archive --worktree-attributes \
--format tar \
--prefix libphonenumber/ \
-o ../libphonenumber_${VERSION}.orig.tar \
master
cd ..
bzip2 libphonenumber_${VERSION}.orig.tar