I'm trying to use the example project at https://github.com/sheehan/job-dsl-gradle-example to create jobs.

1. I created a new job that uses this repo as the SCM.
2. Add an Invoke Gradle build step, use gradle wrapper, invoking clean test workspace
3. Add a 'process job dsl' build step, using 'build/workspace/*/.groovy' as the scripts

Result:

[Gradle] - Launching build.
[workspace] $ /home/marc/.jenkins/jobs/job-dsl-example-thingie/workspace/gradlew clean test workspace
:clean
:compileJava UP-TO-DATE
:compileGroovy
:processResources UP-TO-DATE
:classes
:compileTestJava UP-TO-DATE
:compileTestGroovy
:processTestResources UP-TO-DATE
:testClasses
:test
:workspace

BUILD SUCCESSFUL

Total time: 7.989 secs
Build step 'Invoke Gradle script' changed build result to SUCCESS
FATAL: org.codehaus.groovy.runtime.InvokerHelper$2 cannot be cast to javaposse.jobdsl.dsl.JobParent
java.lang.ClassCastException: org.codehaus.groovy.runtime.InvokerHelper$2 cannot be cast to javaposse.jobdsl.dsl.JobParent
at javaposse.jobdsl.dsl.DslScriptLoader.runDslEngineForParent(DslScriptLoader.java:64)
at javaposse.jobdsl.dsl.DslScriptLoader.runDslEngine(DslScriptLoader.java:89)
at javaposse.jobdsl.plugin.ExecuteDslScripts.perform(ExecuteDslScripts.java:177)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:770)
at hudson.model.Build$BuildExecution.build(Build.java:199)
at hudson.model.Build$BuildExecution.doRun(Build.java:160)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:533)
at hudson.model.Run.execute(Run.java:1759)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:89)
at hudson.model.Executor.run(Executor.java:240)