The URL of an API endpoint which establishes a client session on successful authentication. Authentication methods supported with this property are WebID, HTTP Basic and HTTP Digest. The endpoint is expected to return a session key as described by sessionKeyName and sessionKeyReceiptLocation. Calls to the service endpoint protected by the security scheme should include the session key if required in the HTTP request location stipulated by sessionKeyLocation. Support for session keys is optional with the above authentication schemes. A service endpoint description need not include this and related properties. e.g. A service may use WebID authentication without session creation by presenting a client certificate to the service endpoint directly without prior login via {sessionAuthorizationUrl}. The API endpoint must support GET.