class ActiveModelSerializers::Adapter::Attributes

def relationship_value_for(association, options)
  return association.options[:virtual_value] if association.options[:virtual_value]
  return unless association.serializer && association.serializer.object
  opts = instance_options.merge(include: @include_tree[association.key])
  relationship_value = Attributes.new(association.serializer, opts).serializable_hash(options)
  if association.options[:polymorphic] && relationship_value
    polymorphic_type = association.serializer.object.class.name.underscore
    relationship_value = { type: polymorphic_type, polymorphic_type.to_sym => relationship_value }
  end
  relationship_value
end