docs: protected String getDefaultTabIndex(HttpServletRequest httpServletRequest) {
          final String stylesheetParameter =
                  this.stylesheetUserPreferencesService.getStylesheetParameter(
                          httpServletRequest, PreferencesScope.STRUCTURE, this.defaultTabParameter);
          if (stylesheetParameter != null) {
              return stylesheetParameter;
          }
  
          final IStylesheetDescriptor stylesheetDescriptor =
                  this.stylesheetUserPreferencesService.getStylesheetDescriptor(
                          httpServletRequest, PreferencesScope.STRUCTURE);
          final IStylesheetParameterDescriptor stylesheetParameterDescriptor =
                  stylesheetDescriptor.getStylesheetParameterDescriptor(this.defaultTabParameter);
          if (stylesheetParameterDescriptor != null) {
              return stylesheetParameterDescriptor.getDefaultValue();
          }
  
          return null;
      }