@Override
    protected <T> Schema<T> writeMessageIdTo(Output output, int fieldNumber,
            Message<T> message) throws IOException
    {
        output.writeString(fieldNumber, message.getClass().getName(), false);

        return message.cachedSchema();
    }
Used by {@link RuntimeSchema#map(Class, Class)}.
protostuff-runtime/src/main/java/io/protostuff/runtime/DefaultIdStrategy.java