code: protected boolean isInvalidResourceName(String resourceName) {
  
          if (resourceName == null) {
              return true;
          }
          try {
  
              m_cms.readResource(resourceName);
              return false;
          } catch (CmsException e) {
              //Ok, resource not valid..
          }
          return true;
      }
docs: Checks if given resource is invalid.<p>
  
  @param resourceName name of resource
  @return true if resourceName is invalid