Bug 67890 [PropertiesView] Exception when entries added to properties view
bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/properties/PropertySheetViewer.java
return getFilteredEntries(entry.getChildEntries());
    }
    /**
     * Returns the child entries of the given category
     * 
     * @param category The category to search
     * 
     * @return the children of the given category (element type
     *         <code>IPropertySheetEntry</code>)
     */
    private List getChildren(PropertySheetCategory category) {
        return getFilteredEntries(category.getChildEntries());
    }
    /*
     * (non-Javadoc) Method declared on Viewer.
     */
    public Control getControl() {
        return tree;
    }
    /**
     * Returns the entries which match the current filter.
     *
     * @param entries the entries to filter
     * @return the entries which match the current filter
     *  (element type <code>IPropertySheetEntry</code>)
     */
    private List getFilteredEntries(IPropertySheetEntry[] entries) {
        
        if (isShowingExpertProperties)