The documentation was referring to an <external-object> tag
which we never implemented
*
* Add @object to the @builder object pool so it can be referenced just like any
* other object built by builder.
- *
- * To make this function even more useful a new special entry point element
- * <external-object> is defined. It is similar to <object> but has
- * to reference an external object exposed with this function.
- * This way you can change properties and even add children to an
- * external object using builder, not just reference it.
*
* Since: 3.8
**/