private static PropertyIsNil parsePropertyIsNilOperator( XMLStreamReader xmlStream )
throws XMLStreamException {
MatchAction matchAction = null;
String s = XMLStreamUtils.getAttributeValue( xmlStream, "matchAction" );
if ( s != null ) {
matchAction = parseMatchAction( xmlStream, s );
}
String nilReason = XMLStreamUtils.getAttributeValue( xmlStream, "nilReason" );
nextElement( xmlStream );
Expression param = parseExpression( xmlStream );
nextElement( xmlStream );
return new PropertyIsNil( param, nilReason, matchAction );
}