java.lang.IllegalArgumentException: Called DataObject.find on null
        at org.openide.loaders.DataObject.find(DataObject.java:477)
        at org.openide.loaders.DataFolder.findFolder(DataFolder.java:536)
        at org.netbeans.modules.visualweb.project.jsfloader.JsfJavaDataObject.handleCopy(JsfJavaDataObject.java:214)
        at org.openide.loaders.DataObject$2.run(DataObject.java:551)
        at org.openide.loaders.DataObjectPool$1WrapAtomicAction.run(DataObjectPool.java:258)
        at org.openide.filesystems.EventControl.runAtomicAction(EventControl.java:120)
        at org.openide.filesystems.FileSystem.runAtomicAction(FileSystem.java:502)
        at org.openide.loaders.DataObjectPool.runAtomicAction(DataObjectPool.java:270)
        at org.openide.loaders.DataObject.invokeAtomicAction(DataObject.java:869)
        at org.openide.loaders.DataObject.copy(DataObject.java:549)
        at org.openide.loaders.DataFolder$Paste$2.handlePaste(DataFolder.java:1628)
        at org.openide.loaders.DataTransferSupport$PasteTypeExt.doPaste(DataTransferSupport.java:176)
        at org.openide.loaders.DataTransferSupport$PasteTypeExt.paste(DataTransferSupport.java:165)
        at org.openide.actions.PasteAction$ActionPT.actionPerformed(PasteAction.java:791)
        at org.netbeans.core.ModuleActions.invokeAction(ModuleActions.java:104)
        at org.openide.actions.PasteAction$ActionPT.run(PasteAction.java:815)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:572)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:997)