code: private boolean hasNavigationProperty(CmsObject cms, CmsResource resource) throws CmsException {
  
          List<CmsProperty> props = cms.readPropertyObjects(resource, false);
          Map<String, String> propMap = CmsProperty.toMap(props);
          return propMap.containsKey(CmsPropertyDefinition.PROPERTY_NAVPOS)
              || propMap.containsKey(CmsPropertyDefinition.PROPERTY_NAVTEXT);
      }
docs: Checks whether a resource has a navigation property.<p>
  
  @param cms the current CMS context
  @param resource the resource to use
  
  @return true if the resource has a navigation property
  
  @throws CmsException if something goes wrong