In merlin, the field 'private TransferHandler transfer' was added to JComponent.
TransferHandler is not Serializable, so if its value is non-null, a JComponent
cannot be serialized.

import javax.swing.*;
import java.io.*;

public class JComponentSerializationTest {
    public static void main(String[] args) throws Exception {
JComponent jcomp = new JLabel();
jcomp.setTransferHandler(new TransferHandler("text"));

FileOutputStream fos = new FileOutputStream(new File("tmp"));
ObjectOutputStream oos = new ObjectOutputStream(fos);

oos.writeObject(jcomp);
    }
}

Exception in thread "main" java.io.NotSerializableException
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1007)
        at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1291)
        at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:367)
        at javax.swing.JComponent.writeObject(JComponent.java:4747)
        at sun.misc.Unsafe.invokeSpecial(Native Method)
        at sun.misc.ClassReflector.invokeSpecial(ClassReflector.java:376)
        at $ClassReflector1.writeObject(Unknown Source)
        at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1260)
        at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1209)
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1005)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:278)
        at JComponentSerializationTest.main(JComponentSerializationTest.java:12)

The field needs to be made transient, and an attempt made to serialze it in
writeObject iff it is Serializable.