code: protected static void iniRole(CmsObject cms, String ou, ComboBox roleComboBox, Log log) {
  
          try {
              List<CmsRole> roles = OpenCms.getRoleManager().getRoles(cms, ou, false);
              CmsRole.applySystemRoleOrder(roles);
              IndexedContainer container = new IndexedContainer();
              container.addContainerProperty("caption", String.class, "");
              for (CmsRole role : roles) {
                  Item item = container.addItem(role);
                  item.getItemProperty("caption").setValue(role.getDisplayName(cms, A_CmsUI.get().getLocale()));
              }
  
              roleComboBox.setContainerDataSource(container);
              roleComboBox.setItemCaptionPropertyId("caption");
              roleComboBox.setNullSelectionAllowed(false);
              roleComboBox.setNewItemsAllowed(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