No, it is a waste of time since ArtifactUnarchiverStep/config.jelly does not even try to support visual configuration. Should just move that blurb into help.html and make the f:block say to look at it (so that the static reference shows docs for the step); and make html.groovy quietly skip over the mappings attribute somehow, without showing the ugly exception.
FWIW this is still present as of Pipeline 2.3 / Jenkins 2.7.3