docs: public Document serviceToDocument() {
          final AtomService service = this;
  
          final Document doc = new Document();
          final Element root = new Element("service", ATOM_PROTOCOL);
          doc.setRootElement(root);
          final List<Workspace> spaces = service.getWorkspaces();
          for (final Workspace space : spaces) {
              root.addContent(space.workspaceToElement());
          }
          return doc;
      }