apply_pending_attributes

# File activemodel/lib/active_model/attribute_registration.rb, line 48
        def apply_pending_attributes(attribute_set)
          superclass.send(__method__, attribute_set) if superclass.respond_to?(__method__, true)

          defined?(@pending_attributes) && @pending_attributes.each do |name, pending|
            attribute_set[name] = pending.apply_to(attribute_set[name])
          end

          attribute_set
        end