Unable to set externalId attribute on outgoing responses

[sleelin]

Currently, the externalId common attribute is marked with a direction of "in". This was intended to ensure it is only ever set in incoming requests, but also means it is stripped from outgoing responses. This appears to be causing Microsoft Entra ID to re-sync every user, as it is using externalId as a sync "anchor".

Expected Behavior

The externalId attribute should not be stripped from outgoing responses.

Actual Behavior

The externalId attribute is stripped from outgoing responses, despite being set.

Steps To Reproduce

1. Include an externalId property in the return value of any egress handler
2. Observe that it has been removed in the outbound message