jenkinsci/copyartifact-plugin — pull request #30 by ikedam (2014-02-11 04:36:59+00:00)
Title: [JENKINS-21274] Fixed startup failure without maven-plugin when compiled with JDK 1.6

It is caused by upcasting.
SEE https://wiki.jenkins-ci.org/display/JENKINS/Tips+for+optional+dependencies for details.

There is no way to reproduce the problem in tests, for jenkins-test-harness depends on maven-plugin.