How to remove a string property of LocalLBMonitorBindingStub

I would like to remove username and password properties.

 

I have: final LocalLBMonitorBindingStub stub = interfaces.getLocalLBMonitor();

 

And I set username and password properties: stub.set_template_string_property(new String[]{monitor.getName()}, new LocalLBMonitorStringValue[] {new LocalLBMonitorStringValue(LocalLBMonitorStrPropertyType.STYPE_USERNAME, monitor.getUserName())});

 

stub.set_template_string_property(new String[]{monitor.getName()}, new LocalLBMonitorStringValue[] {new LocalLBMonitorStringValue(LocalLBMonitorStrPropertyType.STYPE_PASSWORD, monitor.getPassword())});

 

How to remove username and password, passing empty password and username doesn't work