# File lib/googleauth/service_account.rb, line 169
      def apply! a_hash, opts = {}
        jwt_aud_uri = a_hash.delete JWT_AUD_URI_KEY
        return a_hash if jwt_aud_uri.nil?
        jwt_token = new_jwt_token jwt_aud_uri, opts
        a_hash[AUTH_METADATA_KEY] = "Bearer #{jwt_token}"
        a_hash
      end