code: protected static void iniRole(CmsObject cms, String ou, com.vaadin.ui.ComboBox<CmsRole> roleComboBox, Log log) {
  
          try {
              List<CmsRole> roles = OpenCms.getRoleManager().getRoles(cms, ou, false);
              CmsRole.applySystemRoleOrder(roles);
  
              DataProvider provider = new ListDataProvider<CmsRole>(roles);
  
              roleComboBox.setDataProvider(provider);
              roleComboBox.setItemCaptionGenerator(role -> {
                  try {
                      return role.getDisplayName(cms, A_CmsUI.get().getLocale());
                  } catch (CmsException e) {
                      return "";
                  }
              });
              roleComboBox.setEmptySelectionAllowed(false);
  
          } catch (CmsException e) {
              if (log != null) {
                  log.error("Unable to read roles.", e);
              }
          }
      }
docs: Initialized the role ComboBox.<p>
  
  @param cms CmsObject
  @param ou to load roles for
  @param roleComboBox ComboBox
  @param log LOG