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                    " (Outdated registry)");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

        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/ExplicitIdStrategy.java