ikedam/backend-update-center2 — pull request #9 by olivergondza (2013-07-29 08:50:20+00:00)
Title: Fix NPE caused by empty Group-Id entry in MANIFEST.MF

Ancient plugins (such as locks-and-latches-plugin) do not have this fields set. Use "org.jvnet.hudson.plugins" as a default.

```
java.lang.NullPointerException
at org.jvnet.hudson.update_center.HPI.isAuthenticJenkinsArtifact(HPI.java:235)
at org.jvnet.hudson.update_center.PluginHistory.findYoungestJenkinsArtifact(PluginHistory.java:102)
at org.jvnet.hudson.update_center.PluginHistory.addArtifact(PluginHistory.java:86)
at org.jvnet.hudson.update_center.LocalDirectoryRepository.listHudsonPlugins(LocalDirectoryRepository.java:143)
at org.jvnet.hudson.update_center.Main.buildPlugins(Main.java:269)
at org.jvnet.hudson.update_center.Main.buildUpdateCenterJson(Main.java:199)
at org.jvnet.hudson.update_center.Main.run(Main.java:163)
at org.jvnet.hudson.update_center.Main.run(Main.java:140)
at org.jvnet.hudson.update_center.Main.main(Main.java:127)
```