class ActiveModel::Serializer

def resource_relationships(adapter_options, options, adapter_instance)
  relationships = {}
  include_directive = options.fetch(:include_directive)
  associations(include_directive).each do |association|
    adapter_opts = adapter_options.merge(include_directive: include_directive[association.key])
    relationships[association.key] ||= relationship_value_for(association, adapter_opts, adapter_instance)
  end
  relationships
end