NoMethodError: undefined method `relation_delegate_class' for Comment:Module

class Post::Base < ActiveRecord::Base
  self.table_name = 'posts'
end

class Post::Special < Post::Base
  has

   private static <T> void register(Map<T, T> substitutions, T annotated, T original, T target) {
        if (annotated != null) {
            guarantee(!substitutions.containsKey(annotated) || substitutions.get(annotated) == original || substitutions.get(annotated) == target, "Already registered: %s", annotated);
            substitutions.put(annotated,