hi, 
i use the exemple code find on the site to create an embed client,
it works find with all transformation.
but now i need barcode and try the extension that is in link on the site, 
barcode4j, and fop never find the extension, is there an option to add to make 
extension work, or is this a bug.

that is my error message :
INFO] building formatting object tree

[INFO] setting up fonts

[ERROR] Unsupported element encountered: barcode (Namespace: 
xmlns:barcode=http://barcode4j.krysalis.org/ns). Source context: unavailable

[ERROR] Expected XSL-FO (root, page-sequence, etc.), SVG (svg, rect, etc.) or 
elements from another supported language.

[ERROR] Unsupported element encountered: code128 (Namespace: 
xmlns:barcode=http://barcode4j.krysalis.org/ns). Source context: unavailable

[ERROR] Unsupported element encountered: height (Namespace: 
xmlns:barcode=http://barcode4j.krysalis.org/ns). Source context: unavailable

[INFO] [1]

[ERROR] no handler defined for 
xmlns:barcode=http://barcode4j.krysalis.org/ns:barcode foreign xml

[INFO] Parsing of document complete, stopping renderer


thanks for the help and to apache community