code: function update( languageTag ) {
           return eventBus.publishAndGatherReplies( `changeLocaleRequest.${locale}`, {
              locale,
              languageTag
           }, noDeliveryToSender ).then( () => {
              tags[ locale ] = languageTag;
           } );
        }
docs: ////////////////////////////////////////////////////////////////////////////////////////////////////// 
  Updates the language tag for the configured locale by emitting the according `changeLocaleRequest`
  event.
  
  @param {String} languageTag
  the language tag to propagate
  
  @return {Promise}
  the promise of the event cycle
  
  @memberof AxI18nHandler