* @throws IllegalArgumentException if the given <code>arg</code> is null or empty
*/
protected void checkPropertyArgument(TokenizerProperty property) throws IllegalArgumentException {
// check the parameter
if (property == null) {
throw new ExtIllegalArgumentException("Property is null.", null );
} else if (property.getImages() == null) {
throw new ExtIllegalArgumentException("No image(s) given in property.", null );
} else if (property.getImages()[0] == null) {
throw new ExtIllegalArgumentException("No (leading) image given in property.", null );
}
}