The content that will be shown in the modal when the user taps the container that holds the DOM children. The
closing of the modal can be triggered by a {@link ILink} that has the ui://modal/close URL. If not found, it
should provide a default method to dismiss the modal, such as tapping outside/on it.
The type is immutable as all constructed node cannot mutable into another derived type
The content that should be shown in normal rendering flow. Can contain a {@link ILink} element with the
ui://modal/openURL that, when tapped, should open themodalcontent in a UI modal widget. If no link element is found with that specific URL, then the whole content triggers the modal popup.