Creates instance data given the serialized form of the data and
the url settings.
url.createData is a function, that function will be called. If
url.createData is a
string, a request to that string will be made. If
url is a string, a
POST request is made to
The serialized data of the instance.
A unique id that represents the instance that is being created.
A promise that resolves to the newly created instance data.