Steps to produce the problem:

1. Install Copy Artifact
2. Disable Maven plugin
3. Restart Jenkins
4. Fails to load Copy Artifact with: (full stacktrace is attached)

   1) Error injecting constructor, java.lang.NoClassDefFoundError: hudson/maven/MavenBuild
     at hudson.plugins.copyartifact.CopyArtifact$DescriptorImpl.<init>(Unknown Source)
   

I found followings:

• This can be reproduced when I package Copy Artifact with jdk 1.6.
• This cannot be reproduced when I package Copy Artifact with jdk 1.7.

It seems that something strange happens in Jenkins plugin loading system.
It may be a problem with guice 4.0 introduced in aea10298 (may be guice does not work with Java1.6).

What I will do are:

• Create a minimum plugin to reproduce the problem.
• Test what happens if reverted aea10298.
• Test what happens if downgrade guice to guice 3.0 (fails to compile?)