code: public CmsLocaleGroup readDefaultFileLocaleGroup(CmsResource resource) throws CmsException {
  
          if (resource.isFolder()) {
              CmsResource defaultFile = m_cms.readDefaultFile(resource, CmsResourceFilter.IGNORE_EXPIRATION);
              if (defaultFile != null) {
                  return readLocaleGroup(defaultFile);
              } else {
                  LOG.warn("default file not found, reading locale group of folder.");
              }
          }
          return readLocaleGroup(resource);
  
      }
docs: Reads the locale group of a default file.<p>
  
  @param resource a resource which might be a folder or a file
  @return the locale group corresponding to the default file
  
  @throws CmsException if something goes wrong