Drag and Drop of JTextField throws "NullPointerException".

When JTextField is Dragged and Dropped an "NullPointerException" is thrown.

How to produce the Bug:
-----------------------
Compile all the attached java files.
Run SampleCode.java.
Try Drag and Drop of JTextField.
If the following Exception is thrown,the bug is reproduced.

Exception:
java.lang.NullPointerException
        at sun.awt.datatransfer.DataTransferer$CharsetComparator.compareCharsets
(DataTransferer.java:1635)
        at sun.awt.datatransfer.DataTransferer$DataFlavorComparator.compare(Data
Transferer.java:1867)
        at java.awt.datatransfer.DataFlavor$TextFlavorComparator.compare(DataFla
vor.java:568)
        at java.util.Collections.max(../../../src/share/classes/java/util/Collec
tions.java:649)
        at java.awt.datatransfer.DataFlavor.selectBestTextFlavor(DataFlavor.java
:526)
        at dndJTextFieldTarget.drop(dndJTextFieldTarget.java:135)
        at java.awt.dnd.DropTarget.drop(DropTarget.java:400)
        at sun.awt.dnd.SunDropTargetContextPeer.processDropMessage(SunDropTarget
ContextPeer.java:584)
        at sun.awt.dnd.SunDropTargetContextPeer.access$800(SunDropTargetContextP
eer.java:58)
        at sun.awt.dnd.SunDropTargetContextPeer$EventDispatcher.dispatchDropEven
t(SunDropTargetContextPeer.java:838)
        at sun.awt.dnd.SunDropTargetContextPeer$EventDispatcher.dispatchEvent(Su
nDropTargetContextPeer.java:776)
        at sun.awt.dnd.SunDropTargetEvent.dispatch(SunDropTargetEvent.java:32)
        at java.awt.Component.dispatchEventImpl(Component.java:3345)
        at java.awt.Container.dispatchEventImpl(Container.java:1361)
        at java.awt.Component.dispatchEvent(Component.java:3327)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3175
)
        at java.awt.LightweightDispatcher.processDropTargetEvent(Container.java:
2945)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:2839)
        at java.awt.Container.dispatchEventImpl(Container.java:1335)
        at java.awt.Window.dispatchEventImpl(Window.java:1338)
        at java.awt.Component.dispatchEvent(Component.java:3327)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:437)
        at java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:14
0)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:126)

        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:121)

        at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)

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