OAuthTokenRequest
Client-credentials token request (POST /oauth/token).
grant_typerequiredstring- Must be `client_credentials` (the only supported grant).One of: client_credentials
client_idrequiredstring- The OAuth2 client id (prefixed `hlmc_`).
client_secretrequiredstring- The OAuth2 client secret (prefixed `hlms_`), shown once at creation.
scopestring- Optional, space-delimited. Narrows the access token to a subset of the client's own scopes; omit to inherit the client's full set.