How to add Connector TEXT via API

Hi All,

In the Figjam UI, if you double click on an arrow, you have the ability to add text to the Connector that stays attached to the Connector. Like this below. 

There HAS to be a way to do this via API; we could not find any properties that sounded like it would create the arrow-embedded-text like the screenshot above. Does this feature exist? 

Thank you!