username must be a non-empty string. Send an object with that field. The route does not define a full request schema or a maximum username length of its own.
The 200 response has this shape:
Unlike the GitHub-data GET route, this handler does not separately map a missing GitHub user to
404. It does not set an explicit public cache policy. Keep integration retries bounded and treat the returned design as a starting point for review.
Source: generation route.