@Override
    protected Class<?> enumClass(int id)
    {
        final RuntimeEnumIO reio = id < enums.size() ? enums.get(id) : null;
        if (reio == null)
            throw new UnknownTypeException("Unknown enum id: " + id);

        return reio.eio.enumClass;
    }
Register a {@link Delegate} and assign an id.
<p>
Delegate ids start at 1.
protostuff-runtime-registry/src/main/java/io/protostuff/runtime/IncrementalIdStrategy.java