public JsfRequestFieldExtractor()
    {
    }

    public void getMetaData(MetaDataWritable metaData, Object entity)
    {
        if (!(entity instanceof DynaForm))
        {
            throw new IllegalArgumentException("passed entity argument not a DynaForm: " + entity);
        }

        create(metaData, (DynaForm) entity);
    }

    /**
     * create the metadata out of the dynaConfigs for the given component
     */
    @SuppressWarnings("unchecked")
    protected void create(MetaDataWritable metaData, DynaForm dynaForm)
    {
        DynaConfigs formConfig = dynaForm.getFormConfigs();
        if (formConfig == null)
        {
            return;
        }

        Iterator<DynaConfig> entries = formConfig.iterator();
        while (entries.hasNext())
        {
            DynaConfig dynaConfig = entries.next();
            String name = dynaConfig.getFor();
            if (name == null)
            {
                throw new IllegalArgumentException("'for' in config tag required");
            }

            if (metaData.isWantedField(name))
            {