owners_by_key

# File activerecord/lib/active_record/associations/preloader/association.rb, line 152
        def owners_by_key
          @owners_by_key ||= owners.each_with_object({}) do |owner, result|
            key = convert_key(owner[owner_key_name])
            (result[key] ||= []) << owner if key
          end
        end