class ExtraColumnsMetaDataProvider implements MetaDataProvider {

    @Override
    public void removeKey(String key)
    {
        if (myExtraColumns.containsKey(key))
        {
            myExtraColumns.remove(key);
        }

        if (myOriginal.hasKey(key))
        {
            myOriginal.removeKey(key);
        }
    }

    protected  ExtraColumnsMetaDataProvider(ExtraColumnsMetaDataProvider source);
    public  ExtraColumnsMetaDataProvider(MetaDataProvider original, Map<String, Object> extraColumns);

}