Incase of windows:
--------------------
The getTextPlainUnicodeFlavor() method returns a DataFlavor which has the following parameters:
        "text/plain;class=java.io.InputStream;charset=utf-16le"
This encode value "utf-16le" is not supported hence the IllegalArgumentException is thrown when it is passed to the getReaderForText method.

The following exception is thrown :

 java.io.UnsupportedEncodingException: utf-16le
        at sun.io.Converters.getConverterClass(Converters.java:97)
        at sun.io.Converters.newConverter(Converters.java:128)
        at sun.io.CharToByteConverter.getConverter(CharToByteConverter.java:71)
        at java.lang.String.getCTBConverter(String.java:154)
        at java.lang.String.getBytes(String.java:662)
        at ReaderForText$TextTransferable.getTransferData(ReaderForText.java:267
)
        at ReaderForText$MenuItemHandler.pasteToClipboard(ReaderForText.java:172
)
        at ReaderForText$MenuItemHandler.actionPerformed(ReaderForText.java:94)
        at java.awt.MenuItem.processActionEvent(MenuItem.java:525)
        at java.awt.MenuItem.processEvent(MenuItem.java:489)
        at java.awt.MenuComponent.dispatchEventImpl(MenuComponent.java:275)
        at java.awt.MenuComponent.dispatchEvent(MenuComponent.java:265)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:322)
        at java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:10
7)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:97)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:88)

Testcase that reproduces this bug:

1)ReaderForText.java : Transferable Class which extends StringSelection.
  

To Run the sample program :

1) Run the ReaderForText.class
2) Do copy and paste operations using the menu items.

Incase of Solaris 2.7:
-----------------------
The charset returned is "iso-10646-ucs-2" . No exception is thrown in this case and so the paste operation is successful.