@Override
    protected <T> HasSchema<T> writePojoIdTo(Output output, int fieldNumber,
            Class<T> clazz) throws IOException
    {
        output.writeString(fieldNumber, clazz.getName(), false);

        // it is important to return the schema initialized (if it hasn't been).
        return getSchemaWrapper(clazz, true);
    }
Used by {@link RuntimeSchema#map(Class, Class)}.
protostuff-runtime/src/main/java/io/protostuff/runtime/DefaultIdStrategy.java