CPS error when running Groovy Jenkins jobs

When running my Java Groovy script and updating to the newest Groovy pipeline. Thank you for your help.

I get this error an exception which occurred: in field locals in field caller in field e in field program in field threads in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@3123aac2 Caused: java.io.NotSerializableException: hudson.model.Run$Artifact

I think the code in question is

stage('Retrieve Code') {
    	FileCacheCountCheck();
    	def job = jenkins.model.Jenkins.instance.getItem("pipeline.preview.build")
    	def build = job.getBuildByNumber(buildNumber)
    	def art = build.artifacts[0]
    	def file = art.file
    	def targetPath = pwd()
    	"rm -rf ${targetPath}/output".execute().text 
    	"rm -rf ${targetPath}/script".execute().text 
    	touch file: "${targetPath}/output/package.tmp"
    	"cp ${file} ${targetPath}/output/package.zip".execute().text
    	"cp -R ${targetPath}@script/ ${targetPath}/script/".execute().text 
    				}
stage('Stash Package') {
	def targetPath = pwd()
	stash includes: 'output/**', name: 'package' 

Based off this article, https://github.com/jenkinsci/pipeline-plugin/blob/master/TUTORIAL.md#serializing-local-variables I tried to use @NonCPS

stage('Retrieve Code') {
	FileCacheCountCheck();
	@NonCPS
	def job = jenkins.model.Jenkins.instance.getItem("pipeline.preview.build")
	@NonCPS
	def build = job.getBuildByNumber(buildNumber)
	@NonCPS
	def art = build.artifacts[0]
	@NonCPS	
	def file = art.file
	@NonCPS
	def targetPath = pwd()
	"rm -rf ${targetPath}/output".execute().text 
	"rm -rf ${targetPath}/script".execute().text 
	touch file: "${targetPath}/output/package.tmp"
	"cp ${file} ${targetPath}/output/package.zip".execute().text
	"cp -R ${targetPath}@script/ ${targetPath}/script/".execute().text 
				}
stage('Stash Package') {
	@NonCPS
	def targetPath = pwd()
	stash includes: 'output/**', name: 'package' 
						}

here is the whole stack trace

an exception which occurred: in field locals in field caller in field e in field program in field threads in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@3123aac2 Caused: java.io.NotSerializableException: hudson.model.Run$Artifact at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:860) at org.jboss.marshalling.river.BlockMarshaller.doWriteObject(BlockMarshaller.java:65) at org.jboss.marshalling.river.BlockMarshaller.writeObject(BlockMarshaller.java:56) at org.jboss.marshalling.MarshallerObjectOutputStream.writeObjectOverride(MarshallerObjectOutputStream.java:50) at org.jboss.marshalling.river.RiverObjectOutputStream.writeObjectOverride(RiverObjectOutputStream.java:179) at java.io.ObjectOutputStream.writeObject(Unknown Source) at java.util.HashMap.internalWriteEntries(Unknown Source) at java.util.HashMap.writeObject(Unknown Source) at sun.reflect.GeneratedMethodAccessor74.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.jboss.marshalling.reflect.SerializableClass.callWriteObject(SerializableClass.java:271) at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:976) at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854) at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032) at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988) at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854) at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032) at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988) at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:967) at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854) at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032) at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988) at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:967) at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854) at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032) at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988) at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854) at org.jboss.marshalling.river.BlockMarshaller.doWriteObject(BlockMarshaller.java:65) at org.jboss.marshalling.river.BlockMarshaller.writeObject(BlockMarshaller.java:56) at org.jboss.marshalling.MarshallerObjectOutputStream.writeObjectOverride(MarshallerObjectOutputStream.java:50) at org.jboss.marshalling.river.RiverObjectOutputStream.writeObjectOverride(RiverObjectOutputStream.java:179) at java.io.ObjectOutputStream.writeObject(Unknown Source) at java.util.TreeMap.writeObject(Unknown Source) at sun.reflect.GeneratedMethodAccessor272.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.jboss.marshalling.reflect.SerializableClass.callWriteObject(SerializableClass.java:271) at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:976) at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854) at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1032) at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:988) at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:854) at org.jboss.marshalling.AbstractObjectOutput.writeObject(AbstractObjectOutput.java:58) at org.jboss.marshalling.AbstractMarshaller.writeObject(AbstractMarshaller.java:111) at org.jenkinsci.plugins.workflow.support.pickles.serialization.RiverWriter.writeObject(RiverWriter.java:140) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:458) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:434) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgramIfPossible(CpsThreadGroup.java:422) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:362) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$100(CpsThreadGroup.java:82) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:242) at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:230) at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:64) at java.util.concurrent.FutureTask.run(Unknown Source) at hudson.remoting.SingleLaneExecutorService$1.run(SingleLaneExecutorService.java:112) at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28) at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Finished: FAILURE