code: public static boolean isValidSchematron (@Nullable final IReadableResource aRes)
    {
      if (aRes == null)
        return false;
  
      return isValidSchematron (TransformSourceFactory.create (aRes));
    }
docs: Check if the passed resource is a valid schematron instance.
  
  @param aRes
  The resource to check. May be <code>null</code>.
  @return <code>true</code> if the schematron is valid, <code>false</code>
  otherwise.