I've encountered a NullPointer in the QNameHelper.suggestPrefix operation.  If the passed-in namespace is null, then the call to .length() will throw a NullPointerException
The proposed fix is to check for null, and if namespace==null return "ns" as is done at the bottom of the method as a last resort for determining a prefix....
public static String suggestPrefix(String namespace)
        if (namespace == null)
            return "ns";

        String result = (String)WELL_KNOWN_PREFIXES.get(namespace);
        if (result != null)
            return result;
        int len = namespace.length();

The attached [patched] file is from the current V1 src tree...the problem exists in both V1 and V2 src trees..
Can we get this patch applied?
Thank you,
Sal Campana

Sal Campana
HP Software