Please also see this thread:
http://jenkins.361315.n4.nabble.com/JIRA-JENKINS-15105-Signature-in-hudson-tasks-Maven-MavenInstaller-json-causes-NullPointerException-td4639778.html
...@googlegroups.comnet.sf.json.JSONException
http://stacktrace.hudson-labs.org/search?query=net.sf.json.JSONException:
Error while setting property=signature type class java.lang.Object
at net.sf.json.JSONObject.toBean(JSONObject.java:577)
http://stacktrace.hudson-labs.org/search/?query=net.sf.json.JSONObject.toBeanentity=method