jenkinsci/jira-plugin — pull request #26 by milkboy (2013-06-12 13:21:03+00:00)
Title: Add hack to get around the "" -> java.net.URL exception (JENKINS-18229)

Apparently parsing empty strings to URL objects has began to fail. No udea why, but adding a customer Stapler Converter is a "dirty hack" to fix it ( JENKINS-18229 )