code: function buildArtifacts( artifacts ) {
        return Promise.all( [
           buildAliases( artifacts ),
           buildFlows( artifacts.flows ),
           buildThemes( artifacts.themes ),
           buildPages( artifacts.pages ),
           buildLayouts( artifacts.layouts, artifacts.themes ),
           buildWidgets( artifacts.widgets, artifacts.themes ),
           buildControls( artifacts.controls, artifacts.themes )
        ] ).then( ( [ aliases, flows, themes, pages, layouts, widgets, controls ] ) => ( {
           aliases,
           flows,
           themes,
           pages,
           layouts,
           widgets,
           controls
        } ) );
     }
docs: //////////////////////////////////////////////////////////////////////////////////////////////////////// 
  @memberOf ArtifactListing
  @param {Object} artifacts
  artifacts collected by the {@link ArtifactCollector}, optionally validated by the
  {@link ArtifactValidator}
  @return {Promise<Object>} the generated listing, ready to be serialized.