Variable submissionAccountSupportPluginConst

Validates that invocations using the Submission capability have a valid accountId that supports the Submission 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 Submission capability URI

This validation applies to all Submission capability invocations (Identity and EmailSubmission method calls) and implements the account capability checks described in RFC 8621 Section 1.3.2.