formatted_payload in resource.rb returns incomplete hash

[Mr5he11]

https://github.com/mailjet/mailjet-gem/blob/675f75f5e402632f4d6a0ab017b680c752fa9ff9/lib/mailjet/resource.rb#L320

When trying to update a Mailjet::Contact through the update_attributes method, the remote instance doesn't get updated. For example:

target = Mailjet::Contact.find("[email protected]")
target.update_attributes("is_excluded_from_campaigns" => true)

doesn't change the remote Contact instance, according to the Mailjet console. Debugging a little bit it turned out that the update api gets called with the return value of formatted_payload as body, and that such method selects only a restricted set of attributes if the local instance is persisted (the linked code row is the exact point where this happens). Is this the correct behaviour?