Credentials used to authenticate requests to the application's service. Only used with
application_uid, and its shape depends on the application server's authentication type:
none: omit.
api_key: { "api_key": string }.
basic: { "username": string, "password": string }.
bearer: { "access_token": string }.
- OAuth2
client_credentials: { "client_id": string, "client_secret": string }
- OAuth2
password: { "username": string, "password": string }
- OAuth2
authorization_code: omit. The channel is created unauthenticated and the OAuth
flow must be completed interactively afterwards.