fUndoable= ! getDestinationPackage().getCompilationUnit(name).exists();
if (getDestinationPackage().getCompilationUnit(name).exists()) makeNotUndoable();
	void doPeform(IProgressMonitor pm) throws JavaModelException{		String name;		String newName= getNewName();		if (newName == null)			name= getCu().getElementName();		else			name= newName;			fUndoable= ! getDestinationPackage().getCompilationUnit(name).exists();				getCu().move(getDestinationPackage(), null, newName, true, pm);	}