When serializing with includeNames, only the first element of array is included in the resulting body if elements don't have id

[marcoherrerarendon]

Awesome job with this library!

As the title states, only the first element of the array is included when the elements don't have an id. I would expect all elements to be included.

According to the JSONAPI spec, included resources do not need to contain an id field. See here for more information.

I created a unit test that showcases the issue. Feel free to clone and run the test.