instance method url_for_direct_upload

# File activestorage/lib/active_storage/service/gcs_service.rb, line 92
    def url_for_direct_upload(key, expires_in:, checksum:, custom_metadata: {}, **)
      instrument :url, key: key do |payload|
        headers = {}
        version = :v2

        if @config[:cache_control].present?
          headers["Cache-Control"] = @config[:cache_control]
          # v2 signing doesn't support non `x-goog-` headers. Only switch to v4 signing
          # if necessary for back-compat; v4 limits the expiration of the URL to 7 days
          # whereas v2 has no limit
          version = :v4
        end

        headers.merge!(custom_metadata_headers(custom_metadata))

        args = {
          content_md5: checksum,
          expires: expires_in,
          headers: headers,
          method: "PUT",
          version: version,
        }

        if @config[:iam]
          args[:issuer] = issuer
          args[:signer] = signer
        end

        generated_url = bucket.signed_url(key, **args)

        payload[:url] = generated_url

        generated_url
      end
    end