Bug 67890 [PropertiesView] Exception when entries added to properties view
bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/properties/PropertySheetEntry.java
public Image getImage() {
        ILabelProvider provider = descriptor.getLabelProvider();
        if (provider == null)
            return null;
        return provider.getImage(editValue);
    }
    /**
     * Returns the parent of this entry.
     * 
     * @return the parent entry, or <code>null</code> if it has no parent
     * @since 3.1
     */
    protected PropertySheetEntry getParent() {
        return parent;
    }
    
    /**
     * Returns an property source for the given object.
     *
     * @param object an object for which to obtain a property source or
     *  <code>null</code> if a property source is not available
     * @return an property source for the given object
     * @since 3.1 (was previously private)
     */
    protected IPropertySource getPropertySource(Object object) {
        if (sources.containsKey(object))
            return (IPropertySource) sources.get(object);
        IPropertySource result = null;
        if (propertySourceProvider != null)
            result = propertySourceProvider.getPropertySource(object);