Hi,

I'm noticing a bug with the following when JSON serializing Embedded Relations:

class Foo
include Mongoid::Document

embeds_many :bars
end

class Bar
include Mongoid::Document

embedded_in :foo
belongs_to :baz
end

class Baz
include Mongoid::Document
end

doesnt_include_full_baz_object = Foo.new.tap do |f|
f.bars << Bar.new(baz: Baz.create)
f.save
end.to_json include: {
bars: {
baz: {}
}
}

1. This includes just the baz_id but not the full baz document itself
   doesnt_include_full_baz_object

I can currently work around this but I would've expected the JSON serializer to return a full Baz document.