We have been doing some tests on the session size of our JSF application using MessAdmin. During these tests we've noticed that MessAdmin is occaisionally reporting that the AjaxStateHolder attribute of the session is not serializable.

This appears to happen only when:

• 
  
• We have a <rich:messages .../> element on the page, and
  
• We add a global faces message to the context (i.e. the client ID is null)
  
  
  The reported stack trace is:
  

  java.lang.NullPointerException
   at java.io.ObjectOutputStream$BlockDataOutputStream.getUTFLength(ObjectOutputStream.java:2097)
   at java.io.ObjectOutputStream$BlockDataOutputStream.writeUTF(ObjectOutputStream.java:1968)
   at java.io.ObjectOutputStream.writeUTF(ObjectOutputStream.java:841)
   at org.richfaces.component.UIRichMessages$FacesMessageWithId.writeObject(UIRichMessages.java:302)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   at java.lang.reflect.Method.invoke(Method.java:597)
   at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:945)
   at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1461)
   at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150)
   at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1509)
   at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1474)
   at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150)
   at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:326)
   at java.util.ArrayList.writeObject(ArrayList.java:570)
   at sun.reflect.GeneratedMethodAccessor83.invoke(Unknown Source)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   at java.lang.reflect.Method.invoke(Method.java:597)
   at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:945)
   at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1461)
   at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1338)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1146)
   at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1509)
   at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1474)
   at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150)
   at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:326)
   at java.util.HashMap.writeObject(HashMap.java:1001)
   at sun.reflect.GeneratedMethodAccessor84.invoke(Unknown Source)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   at java.lang.reflect.Method.invoke(Method.java:597)
   at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:945)
   at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1461)
   at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392)
   at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150)
   at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:326)
  

  
  
  Looking at the implementation, it would appear that writeUTF is being used for strings which could potentially be null.
  
  Has anyone else seen this issue?