Bug 67890 [PropertiesView] Exception when entries added to properties view
bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/properties/PropertySheetViewer.java
TreeItem item = null;
        TreeItem[] childItems;
        if (node == rootEntry) {
            childItems = tree.getItems();
        } else {
            item = (TreeItem) widget;
            childItems = item.getItems();
        }
        
        if (item != null && !item.getExpanded()) {
            
            for (int i = 0; i < childItems.length; i++) {
                if (childItems[i].getData() != null) {
                    removeItem(childItems[i]);
                }
            }
            
            if (category != null || entry.hasChildEntries()) {
                
                
                
                
                
                
                
                
                if (childItems.length != 1 || childItems[0].getData() != null)
                    
                    new TreeItem(item, SWT.NULL);
            }