Cin7 Omni API: query Contact via secondary contact email address in where clause

To answer a question like “do we have a secondary contact record associated with a particular email address”, it doesn't seem like the Cin7 Omni API has a method for querying to answer this question.

While it's possible to lookup primary contact records via the ‘Email’ field, trying to do the same for secondary contact email addresses results in the following:

GET /api/v1/Contacts?where=SecondaryContacts.Email='example@email.com'

400 Invalid WHERE clause; 'SecondaryContacts.Email' is not a valid field.

Would love to see support added for this.