Hi Lyon,
There's more modern way than using the cocoon one. Luckly sling project does not force us to use it. Hene we can rely on org.xml packages.
Please see following excellent blog post by @ Imran Khan:
https://medium.com/@toimrank/link-checker-and-transformer-381d4f245d12
Here, we are using org.xml.sax.helpers.AttributesImpl as alternative to org.apache.cocoon.xml.sax.AttributesImpl and AbstractSAXPipe is no longer needed in this implementation.
Regards,
Peter