docs: public CmsRelationType addRelationType(String name, String type) throws CmsConfigurationException {
  
          // check if new relation types can still be added
          if (m_frozen) {
              throw new CmsConfigurationException(Messages.get().container(Messages.ERR_NO_CONFIG_AFTER_STARTUP_0));
          }
  
          CmsRelationType relationType = new CmsRelationType(m_configuredRelationTypes.size(), name, type);
          m_configuredRelationTypes.add(relationType);
          return relationType;
      }