Parameter of type xs:anyURI

Hey list,

I don't get how to define a parameter of type xs:anyURI. I try it like this:

<xsl:param name="base-uri" select="'http://www.google.com'" as="xs:anyURI"/>

But Saxon 9 gives me an error:
"Error at xsl:param on ...:
XTTE0600: Required item type of value of parameter $base-uri is
xs:anyURI; supplied value has item type xs:string"

Do I always have to cast a string value with xs:anyURI()?
What if I pass the value from Java, do I need 2 parameters then -- one
for the string value, and the other one casted as xs:anyURI?

Thanks,

Martynas
semantic-web.dk