KSQL with authenticated kafka connect

The documentation on how to get this up is lacking, but with a bit of trial and horror and reading the source this seems to work:

ksql.connect.url=https://url.to.your.kafka.connect
ksql.connect.basic.auth.credentials.source=FILE
ksql.connect.basic.auth.credentials.file=/path/to/foo.properties

where foo.properties contains

username: fred
password: obviouslythisisnotreallymypassword