has_and_belongs_to_many does not use eager loading with { inverse_of: nil }

class Car

  include Mongoid::Document

end

class Person

  include Mongoid::Document

  has_and_belongs_to_many :cars, inverse_of: nil

end

Car.delete_all

Person.delete_all

person = Person.create!

10.times do |i|

  person.cars << Car.create!

end

person = Person.includes( :cars ).first

# cars are not loaded 

# person.ivar( :cars ) === false