Remote EJB Marshalling failing with ClassCastException: Cannot cast java.util.TreeMap to ... , when using Collections.emptySortedMap() in JBoss EAP 7

Environment

Red Hat JBoss Enterprise Application Platform (EAP) 7.3

Issue

• Remote EJB Marshalling failing with ClassCastException: Cannot cast java.util.TreeMap to ... , when using Collections.emptySortedMap() in JBoss EAP 7

The class being serialized is :

import java.io.Serializable;
import java.util.Collections;
import java.util.Date;
import java.util.SortedMap;
import java.util.TreeMap;

public class Example implements Serializable {
  private static final long serialVersionUID = 3L;  
  private SortedMap<String, String> map = Collections.emptySortedMap();
  private Date mop;
}

The exception is:

     [java] java.lang.ClassCastException: Cannot cast java.util.TreeMap to java.util.Date
     [java] 	at java.lang.Class.cast(Class.java:3369)
     [java] 	at org.jboss.marshalling.reflect.SerializableField.setObject(SerializableField.java:342)
     [java] 	at org.jboss.marshalling.river.RiverUnmarshaller.readFields(RiverUnmarshaller.java:1864)
     [java] 	at org.jboss.marshalling.river.RiverUnmarshaller.doInitSerializable(RiverUnmarshaller.java:1778)
     [java] 	at org.jboss.marshalling.river.RiverUnmarshaller.doReadNewObject(RiverUnmarshaller.java:1406)
     [java] 	at org.jboss.marshalling.river.RiverUnmarshaller.doReadObject(RiverUnmarshaller.java:283)
     [java] 	at org.jboss.marshalling.river.RiverUnmarshaller.doReadObject(RiverUnmarshaller.java:216)
     [java] 	at org.jboss.marshalling.AbstractObjectInput.readObject(AbstractObjectInput.java:41)
     [java] 	at WriteReadExample.read(WriteReadExample.java:83)
     [java] 	at WriteReadExample.test(WriteReadExample.java:29)
     [java] 	at WriteReadExample.main(WriteReadExample.java:20)
     [java] Caused by: an exception which occurred:
     [java] 	in field Example.mop
     [java] 	in object Example@458c1321
     [java] 	in object of type Example

Resolution

Apply the latest cumulative patch / update that resolves This content is not included.JBEAP-20245

Workaround:

Change from :

  private SortedMap<String, String> map = Collections.emptySortedMap();
  private Date mop; 

to:

  private SortedMap<String, String> map = new TreeMap<String,String>();
  private Date mop; 

Root Cause

This content is not included.JBEAP-20245 - Cannot cast java.util.TreeMap to java.util.Date , if Collections.emptySortedMap(); and Date field name sorts after Map

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