Bug 67890 [PropertiesView] Exception when entries added to properties view
bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/properties/PropertySheetEntry.java
private ListenerList listeners = new ListenerList();
    /**
     * Create the CellEditorListener for this entry. It listens for
     * value changes in the CellEditor, and cancel and finish requests.
     */
    private ICellEditorListener cellEditorListener = new ICellEditorListener() {
        public void editorValueChanged(boolean oldValidState,
                boolean newValidState) {
            if (!newValidState)
                
                setErrorText(editor.getErrorMessage());
            else
                 
                setErrorText(null);
        }
        public void cancelEditor() {
            setErrorText(null);
        }
        public void applyEditorValue() {
            PropertySheetEntry.this.applyEditorValue();
        }
    };
    /* (non-Javadoc)
     * Method declared on IPropertySheetEntry.
     */
    public void addPropertySheetEntryListener(
            IPropertySheetEntryListener listener) {
        listeners.add(listener);
    }
    /* (non-Javadoc)