(I'm a quite new user and contributor of Mongoid. Hello everyone and thanks for the awesome work! :+1

In add_counter_cache_callbacks method, the only callbacks that are added are after_create and before_destroy.

What about when the association is updated?

In my case, I have 2 models Company and User:

class User
  include Mongoid::Document
  belongs_to :company, counter_cache: true
end

class Company
  include Mongoid::Document
  field :users_count, type: Integer, default: 0
  has_many :users
end

When I update a User to change his Company, the users_count is not updated. The counter for the former Company is not decremented, and the counter for the new Company is not incremented.

Maybe I missed something, but shouldn't add_counter_cache_callbacks also implement before_update and after_update? or should it rather implement the new Relation Callbacks?