code: public CmsResource readDefaultFile(String resourceNameOrID) throws CmsException, CmsSecurityException {
  
          return readDefaultFile(resourceNameOrID, CmsResourceFilter.DEFAULT);
      }
docs: Returns the default resource for the given folder.<p>
  
  If the given resource name or id identifies a file, then this file is returned.<p>
  
  Otherwise, in case of a folder:<br>
  <ol>
  <li>the {@link CmsPropertyDefinition#PROPERTY_DEFAULT_FILE} is checked, and
  <li>if still no file could be found, the configured default files in the
  <code>opencms-vfs.xml</code> configuration are iterated until a match is
  found, and
  <li>if still no file could be found, <code>null</code> is returned
  </ol>
  
  @param resourceNameOrID the name or id of the folder to read the default file for
  
  @return the default file for the given folder
  
  @throws CmsException if something goes wrong
  @throws CmsSecurityException if the user has no permissions to read the resulting file