The tag is present in Lintian version 2.109.3. That is the most recent version we know about.
The package declares a depends on a virtual package without listing a real package as an alternative first.
If this package could ever be a build dependency, it should list a real package as the first alternative to any virtual package in its Depends. Otherwise, the build daemons will not be able to provide a consistent build environment.
If it will never be a build dependency, this isn't necessary, but you may want to consider doing so anyway if there is a real package providing that virtual package that most users will want to use.