Thanks for looking into this so quickly. Agree that it is no longer a blocker. An alternative fix is to just upgrade to the new method. Though quoting it would ensure it works on older versions too. I understand your concerns about not necessarily wanting to change the closure strategy for this as this is probably an edge case. Feel free to close as won't fix since there is a reasonably easy workaround.

I reduced the priority since there is a workaround.

The problem is that startsWithParameters calls the new startsWithParameters method of BuildPipelineView which then internally adds a new WithXmlAction and that causes the ConcurrentModificationException.

To avoid this, the startsWithParameters element name in the configure block should be quoted:

...
    configure { pipelineNode ->
        pipelineNode << {
            'startsWithParameters'(true)
        }
    }
...

This will happen for other element names when a method with the same name exists in the scope. I'm not sure if changing the closures resolution strategy will help or break other things.

So I had previously added my own configure block to turn this parameter on before it was supported in the DSL with a block that looks like the following. When I replaced that with the new startsWithParameters block it worked.

jobFactory.view(type: 'BuildPipelineView') {
    name("myPipeline")
    showPipelineParameters true
    showPipelineParametersInHeaders false
    showPipelineDefinitionHeader true
			
    selectedJob("ajob")
    configure { pipelineNode ->
	pipelineNode << {
	    startsWithParameters true
        }
   }
}

The seems to be a similary issue as JENKINS-22708, but only for views.

Can you check that your configure blocks for views are escaping calls to properties? Have a look at 4th bullet point on https://github.com/jenkinsci/job-dsl-plugin/wiki/The-Configure-Block#transforming-xml.