346.15.

XPathBuilder.xpath("/foo:person/@id", String.class).logNamespaces()

<xpath logNamespaces="true" resultType="String">/foo:person/@id</xpath>

2012-01-16 13:23:45,878 [stSaxonWithFlag] INFO  XPathBuilder  - Namespaces discovered in message:
{xmlns:a=[http://apache.org/camel], DEFAULT=[http://apache.org/default],
xmlns:b=[http://apache.org/camelA, http://apache.org/camelB]}