OptionalchannelOptionallocaleOptionaluserOptionalgetThe URL of the Endpoint the Session was created on, if known.
OptionalgetThe Subscription with that id owned by this Session, or null.
A SubscriptionId is only meaningful inside the Session that created it (Part 4), so a
Subscription of another Session is null here as much as one that never existed.
Optional: an in-process caller (PseudoSession, tests) has no Subscriptions to check
against, and a Method validating its SubscriptionId argument then lets it through.
The localeIds of the Session's last successful ActivateSession, most preferred first. OPC 10000-4 v1.05.07 §5.7.3: a later ActivateSession with a null/empty localeIds keeps this list unchanged. Empty (or absent) until the Session has been activated once.