[SOLVED] Quick fix doesn't work

Hello,
I'm writing my own QuickFix in MetaDataError class. The code looks like this:

public class BadColorMetaDataError extends ImageMetaDataError {

	private boolean color = true; 

	public BadColorMetaDataError(InputPort inputPort, String message, boolean color) {
		super(Severity.ERROR, inputPort, message);
		this.color = color;
	}

@Override
	public List<? extends QuickFix> getQuickFixes() {
		List<QuickFix> list = Collections.<QuickFix>emptyList();
		if(color){
			list.add(new OperatorInsertionQuickFix("insert_gs_to_color", new Object[0], 10, (InputPort)getPort()) {

@Override
				public Operator createOperator() throws OperatorCreationException {
					Operator op = OperatorService.createOperator(GrayScaleToColorOp.class);
					return op;
				}
			});
		} else {
			list.add(new OperatorInsertionQuickFix("insert_color_to_gs", new Object[0], 10, (InputPort)getPort()) {

@Override
				public Operator createOperator() throws OperatorCreationException {
					Operator op = OperatorService.createOperator(ColorToGrayScaleOp.class);
					return op;
				}
			});

		}
		return list;
	}
}

My ErrorsImage.properties file defined in build.xml by

<property name="extension.errorDescription" value="/com/rapidminer/resources/i18n/ErrorsImage.properties" />

looks like this:

metadata.quickfix.insert_color_to_gs = Insert Color to Grayscale operator.
metadata.quickfix.insert_gs_to_color = Insert Grayscale to Color operator.

When I run RapidMiner, I get this error:

Exception in thread "AWT-EventQueue-0" java.lang.UnsupportedOperationException
	at java.util.AbstractList.add(AbstractList.java:148)
	at java.util.AbstractList.add(AbstractList.java:108)
	at com.burgsys.image.core.ioobjects.metadata.errors.BadColorMetaDataError.getQuickFixes(BadColorMetaDataError.java:28)
	at com.rapidminer.gui.flow.ErrorTable$4.getValueAt(ErrorTable.java:249)
	at com.rapidminer.gui.tools.ExtendedJTableSorterModel.getValueAt(ExtendedJTableSorterModel.java:328)
	at javax.swing.JTable.getValueAt(JTable.java:2716)
	at javax.swing.JTable.prepareRenderer(JTable.java:5714)
	at javax.swing.plaf.basic.BasicTableUI.paintCell(BasicTableUI.java:2114)
	at javax.swing.plaf.basic.BasicTableUI.paintCells(BasicTableUI.java:2016)
	at javax.swing.plaf.basic.BasicTableUI.paint(BasicTableUI.java:1812)
	at javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)
	at javax.swing.JComponent.paintComponent(JComponent.java:778)
	at javax.swing.JComponent.paint(JComponent.java:1054)
	at javax.swing.JComponent.paintChildren(JComponent.java:887)
	at javax.swing.JComponent.paint(JComponent.java:1063)
	at javax.swing.JViewport.paint(JViewport.java:731)
	at javax.swing.JComponent.paintChildren(JComponent.java:887)
	at javax.swing.JComponent.paint(JComponent.java:1063)
	at javax.swing.JComponent.paintChildren(JComponent.java:887)
	at javax.swing.JComponent.paint(JComponent.java:1063)
	at javax.swing.JComponent.paintChildren(JComponent.java:887)
	at javax.swing.JComponent.paint(JComponent.java:1063)
	at javax.swing.JComponent.paintChildren(JComponent.java:887)
	at javax.swing.JComponent.paint(JComponent.java:1063)
	at javax.swing.JComponent.paintChildren(JComponent.java:887)
	at javax.swing.JSplitPane.paintChildren(JSplitPane.java:1047)
	at javax.swing.JComponent.paint(JComponent.java:1063)
	at com.vlsolutions.swing.docking.SplitContainer.paint(SplitContainer.java:192)
	at javax.swing.JComponent.paintToOffscreen(JComponent.java:5221)
	at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1512)
	at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1443)
	at javax.swing.RepaintManager.paint(RepaintManager.java:1236)
	at javax.swing.JComponent._paintImmediately(JComponent.java:5169)
	at javax.swing.JComponent.paintImmediately(JComponent.java:4980)
	at javax.swing.RepaintManager$3.run(RepaintManager.java:796)
	at javax.swing.RepaintManager$3.run(RepaintManager.java:784)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
	at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:784)
	at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:757)
	at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:706)
	at javax.swing.RepaintManager.access$1000(RepaintManager.java:62)
	at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1651)
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:727)
	at java.awt.EventQueue.access$200(EventQueue.java:103)
	at java.awt.EventQueue$3.run(EventQueue.java:688)
	at java.awt.EventQueue$3.run(EventQueue.java:686)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:697)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

And I really don't know where should I look for problem. Can somebody point me where to start.
Thanks for your responses.

Best,
Vaclav