Possibly similar to https://issues.jenkins-ci.org/browse/JENKINS-16361 in dsl-plugin.

Scriptler Groovy scripts using the @Grape annotation fail with:

Execution of script [CiDbPoller.groovy] failed - java.lang.NoClassDefFoundError: org/apache/ivy/core/report/ResolveReportorg.jenkinsci.plugins.scriptler.util.GroovyScript$ScriptlerExecutionException: java.lang.NoClassDefFoundError: org/apache/ivy/core/report/ResolveReport
at org.jenkinsci.plugins.scriptler.util.GroovyScript.call(GroovyScript.java:108)

In the issue related to dsl plugin, it seems that there is a resolution available. It would be nice if it could be applied here as well.