Fix.

Author: beauby

lib/active_model/serializer.rb

@@ -62,7 +62,7 @@ def self.attribute(attr, options = {})
       ActiveModelSerializers.silence_warnings do
         define_method key do
           object.read_attribute_for_serialization(attr)
-        end unless (key != :id && method_defined?(key)) || _fragmented.respond_to?(attr)
+        end unless method_defined?(key) || _fragmented.respond_to?(attr)
       end
     end