Bug 33040 No single Undo for generate delegate methods
RC 1 - JUnit setup - open TestCase - select fName - generate delegate methods for all String methods - press Ctrl+Z Observe: only one method is removed.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/actions/AddGetterSetterAction.java
}	
	private void showError(String message) {
		MessageDialog.openError(getShell(), dialogTitle, message);
	}
	
	/*
	 * Returns fields in the selection or <code>null</code> if the selection is 
	 * empty or not valid.
	 */
	private IField[] getSelectedFields(IStructuredSelection selection) {
		List elements= selection.toList();
		int nElements= elements.size();
		if (nElements > 0) {
			IField[] res= new IField[nElements];
			ICompilationUnit cu= null;
			for (int i= 0; i < nElements; i++) {
				Object curr= elements.get(i);
				if (curr instanceof IField) {
					IField fld= (IField)curr;
					
					if (i == 0) {
						
						cu= fld.getCompilationUnit();
						if (cu == null) {
							return null;
						}
					} else if (!cu.equals(fld.getCompilationUnit())) {
						
						return null;
					}