You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: design_reference_filter.rb
    path of file: ./repos/gitlabhq/lib/banzai/filter/references
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module Banzai
  module Filter
    module References
      class DesignReferenceF
    
        def parent_records(project, identifiers)
          return [] unless project.design_management_enabled?

          iids        = identifiers.map(&:issue_iid).to_set
          issues      = project.issues.where(iid: iids).includes(:project, :namespace)
          id_for_iid  = issues.index_by(&:iid).transform_values(&:id)
          issue_by_id = issues.index_by(&:id)

          designs(identifiers, id_for_iid).each do |d|
            issue = issue_by_id[d.issue_id]
            # optimisation: assign values we have already fetched
            d.project = project
            d.issue = issue
          end
        end