Built-in capabilities apparently use some mechanism to define that certain parameters are required, as in deviceNotification for the Notification capability:
Actually - the answer is in fact in that paragraph you referenced (emphasis mine):
Name is the value that shows up where "ENUM" used to be, directly above the input. If the name ends with an asterisk (*) it will be considered required and the input box will be red and the button will not submit without a value
Clearly I should have read that post a second time! For some reason I thought the asterisk feature was only related to ENUM, but your OP screenshot clearly shows its use with a string. Glad to be of (indirect) help!