any known issues with Xalan 2.7.1 distributed with Sun's JRE 6?

Hi all,

I am trying to implement few XSL extension functions in Java and call 
them from my XSL template.

I discovered that the ExpressionContext interface is not available and 
so all the org.apache namespace (there is something like 
com.sum.org.apache...internal.ExpressionContext but the compiler refuses 
it).

Also discovered that no matter what the referenced FQCN is, the XSL 
process always tries to invoke methods in the java.lang.String class.

For example

<xsl:stylesheet version="1.0"
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns:xalan="http://xml.apache.org/xalan"
   xmlns:utils="com.acme.followed.by.this.garbage:@%#$%@#^#%#$"
   extension-element-prefixes="utils">


Then this one works by calling the java.lang.String.length method !

     <xsl:value-of select="utils:length('fff')" />

Regards,
Adrian.