The abs2rel command takes exactly two arguments - a destination path and a base path. It determines relative path from the base path to the destination path and prints it on standard output.
abs2rel /1/2/3/a/b/c /1/2/3 will print a/b/c on standard output.
abs2rel foo/bar foo/baz will print ../bar on standard output.
Bugs should be reported through Java Packages Tools issue tracker at Github: m[blue]https://github.com/fedora-java/javapackages/issuesm[].