The tag is present in Lintian version 2.104.232. That is the most recent version we know about.
This package installs a file or directory whose name ends in whitespace. This might be intentional but it's normally a mistake. If it is intentional, add a Lintian override.
One possible cause is using debhelper 5.0.57 or earlier to install a doc-base file with a Document field that ends in whitespace.