After the JENKINS-31661 introduction, Paul Milliken and Omar Kohl reported troubles with the too strict validation.
We need to be more lenient especially with the TLDs.
Allow trailing dot in Root URL
Jenkins.rootUrl too often unset or incorrect
I am calling it an issue taking the community rating feedback. It will require backporting to LTS if 2.119 is selected
Code changed in jenkins
User: Wadeck Follonier
JENKINS-51064 Lenient URL validator for Root URL (#3415)
*NOTE:* This service been marked for deprecation: https://developer.github.com/changes/2018-04-25-github-services-deprecation/
Functionality will be removed from GitHub.com on January 31st, 2019.
Fixed in version 2.120, but there is a followup ticket JENKINS-51158 to address some further problems.