Incorrect documentation of API parameters

[crazyscientist]

Issue Description

After #9715 explained the difference between a "boolean flag" parameter and "boolean value" parameters, the issue was closed with the reason that the parameters of the /source/<project> endpoint are boolean and documented as such.

Unfortunately, these parameters are not declared as boolean:

Expected Result

Any boolean flag parameter (i.e. true, if present, and false otherwise) of any endpoint should be declared as such.¹

Footnotes

1. For clients interacting with the API directly, it is very frustrating: One has to figure out this distinction by trial and error. ↩

[bmwiedemann]

Please review #13984