The tag is present in Lintian version 2.104.234. That is the most recent version we know about.
This icon file couldn't be found. If the path to the icon in the
menu file is an absolute path, make sure that icon exists at that path in
the package. If the path is relative or a simple filename, make sure the
icon is installed in
/usr/share/pixmaps, the default location.
If the icon is provided by another package on which this package depends, Lintian may not be able to determine that icon pages are available. In this case, after confirming that all icons are available after this package and its dependencies are installed, please add a Lintian override.
Refer to Debian Menu System section 3.7 for details.