Variable vacationResponseAccountSupportPluginConst

Validates that invocations using the VacationResponse capability have a valid accountId that supports the VacationResponse capability.

This plugin performs three critical validation checks:

1. Verifies the invocation includes a valid accountId argument (non-empty string)
2. Confirms the account exists in the session's accounts collection
3. Ensures the account's accountCapabilities includes the VacationResponse capability URI

This validation applies to all VacationResponse capability invocations (VacationResponse/get and VacationResponse/set) and implements the account capability checks described in RFC 8621 Section 1.3.3.