SOAPFaultException cannot render SOAP 1.2 Fault Subcode

The code below doesn't render <soapenv:Subcode>:

import javax.xml.soap.SOAPConstants;
import javax.xml.soap.SOAPFactory;
import javax.xml.soap.SOAPFault;
import javax.xml.ws.soap.SOAPFaultException;
...
SOAPFactory factory = SOAPFactory.newInstance(SOAPConstants.SOAP_1_2_PROTOCOL);
SOAPFault fault = factory.createFault("Operator not found", new QName(SOAPConstants.URI_NS_SOAP_1_2_ENVELOPE, "Receiver"));
fault.appendFaultSubcode(new QName("...", "OperatorNotFound"));
...
throw new SOAPFaultException(fault);