The published targets now render as prometheus scrape jobs, so the
option's name is true: the collector reaches them by name over https,
using prometheus-native oauth2 with the audience set to the target's own
url. Registered is not the same as requested — a client that does not
ask for an audience gets a token with an empty one however complete its
registration looks.
The url is split into scheme, target and metrics_path rather than asked
for three times: two spellings of one address is a mismatch waiting to
happen, and the failure it produces is a valid token refused at the
target. A malformed or non-https url is an assertion rather than a null
dereference from inside the renderer.