Jenkinsfile: How to iterate a properties file without having an "java.io.NotSerializableException: java.util.Hashtable$Entry" error

[eid badr]

Hi

in jenkinsFile.groovy I want to iterate over a properties file, but I always get an error
how can it be done properly with no error?

node('master') {
    Properties properties = new Properties()
    properties.load(new FileInputStream("${env.JENKINS_HOME}\\properties\\${file}"))

    for(Entry<Object, Object> en : properties.entrySet()) {
        System.out.println(en);
    }

    /*for(Object k:properties.keySet()) {
        String key = (String) k;
    } */ // same error
 /*   Enumeration en = properties.propertyNames();
    while (en.hasMoreElements()) {
        String key = (String) en.nextElement();
        System.out.println(key + " -- " + properties.getProperty(key));
    }*/ // same error
}

java.io.NotSerializableException: java.util.Hashtable$Entry
	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.GeneratedMethodAccessor126.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.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.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.GeneratedMethodAccessor424.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:132)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:429)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.saveProgram(CpsThreadGroup.java:408)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:356)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$100(CpsThreadGroup.java:78)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:236)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:224)
	at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:47)
	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)
Caused by: an exception which occurred:
	in field locals
	in field parent
	in field caller
	in field e
	in field program
	in field threads
	in object org.jenkinsci.plugins.workflow.cps.CpsThreadGroup@19eb7bd
Finished: FAILURE

[Sverre Moe]

Put it in a method annotated with @NonCPS

[eid badr]

Thank you, it worked