Update or create a contact.
email or userId to identify the contact you want to update.email or userId value. If a contact is found for one of the
values (e.g. email), the other value (e.g. userId) will be updated. If a
contact is not found, a new contact will be created using both email and
userId values.userId is not provided.email is not provided.boolean denoting if the contact should be added (true) or removed (false) from the list. Read
morestring, number, boolean or date (see allowed date formats).
400 Bad Request.