SOAPUI 5.3.0 Error - Ambiguous method overloading for method com.eviware.soapui.support.XmlHolder

Hi,

I am trying to use Groovyscript in an assertion in SOAPUI 5.3.0, and I am getting this error:

"Ambiguous method overloading for method com.eviware.soapui.support.XmlHolder#<init>.
Cannot resolve which method to invoke for [null] due to overlapping prototypes between:
[interface org.apache.xmlbeans.XmlObject]
[interface org.w3c.dom.Node]"

I have cut the code in the assertion down to this:

import com.eviware.soapui.settings.SSLSettings
import com.eviware.soapui.SoapUI
import org.apache.log4j.Logger;
import com.eviware.soapui.support.UISupport;
import com.eviware.soapui.support.XmlHolder

def xml = messageExchange.modelItem.testStep.getParent().getParent().getTestCaseByName("Test Setup").getTestStepByName("Get Security Domain").getProperty("Response").getValue();
def holder = new XmlHolder(xml)

and it looks like the last line, the "def holder = new XmlHolder(xml)", is causing the problem.

If I remove or comment out that line, the script runs without error, but if I have that line in the script assertion I get the error above!!

Can anyone tell me what is causing this error, and how I can eliminate the problem?

Thanks,

Jim