There should be a default automatic decorator turned on, which adds target="_blank" and rel="noopener noreferrer" attributes to all external links (links starting with http://, https:// or //).
There should be no changes to the model or the view of the editors.
Decorator data should be added during downcast (run window.editors.automaticDecorators.getData() to see how it works).
There are 2 additional decorators in this editor:
phone, which detects all links starting with tel: and adds the phone CSS class to such link,
internal, which adds the internal CSS class to all links starting with #.