docs: public Collection<String> getAdditionalStyleSheets() {
  
          if (m_additionalStyleSheets == null) {
              Set<String> stylesheets = new LinkedHashSet<>();
              for (I_CmsWorkplaceStylesheetProvider provider : ServiceLoader.load(
                  I_CmsWorkplaceStylesheetProvider.class)) {
                  stylesheets.addAll(provider.getStylesheets());
              }
              m_additionalStyleSheets = Collections.unmodifiableSet(stylesheets);
          }
          return m_additionalStyleSheets;
      }