Can be used to add an identifier to the client from an external system, must be unique
Any of:
{ "id": "string", "external_id": "string", "external_origin": "string", "name": "string", "shortcode": "string", "primary_contact": { "id": "string", "first_name": "string", "last_name": "string", "email": "string", "type": "user", "space": { … } }, "origin_space": { "id": "string", "name": "string" } }