When creating an event with the API:
https://developers.google.com/google-apps/calendar/v3/reference/events/insert
If I fill in the source.title and source.url fields:
source.title string The name of the source; for example, the name of a webpage or email subject. source.url string is the URL of the source pointing to the resource. URL scheme must be HTTP or HTTPS.
With the old interface in the event, I could see a read-only field between the "Calendar" and the "Description":
Source [Link Icon] The name of my link, from [source.title]
And "The name of my link from [source.title]" was a link to [source.url]
![Old user interface](https://fooobar.com//img/aaae7861e1cf50534d1318bb303cf24e.png)
:
[ ] . [ ]
[ ] [source.url]
![New user interface](https://fooobar.com//img/a32f972556c8ec7a83d127deeae31224.png)
- ? API, ?
: https://issuetracker.google.com/issues/73334552