code: public static boolean isModelCopyGroup(CmsObject cms, CmsResource resource) {
  
          boolean result = false;
          if (isModelGroup(resource)) {
              try {
                  CmsProperty tempElementsProp = cms.readPropertyObject(
                      resource,
                      CmsPropertyDefinition.PROPERTY_TEMPLATE_ELEMENTS,
                      false);
                  if (!tempElementsProp.isNullProperty()
                      && CmsContainerElement.USE_AS_COPY_MODEL.equals(tempElementsProp.getValue())) {
                      result = true;
                  }
              } catch (CmsException e) {
                  LOG.warn(e.getMessage(), e);
              }
  
          }
          return result;
      }
docs: Checks whether the given resource is a model reuse group.<p>
  
  @param cms the cms context
  @param resource the resource
  
  @return <code>true</code> in case the resource is a model reuse group