肥皂响应的php null属性

I'm doing SOAP request to a server in WSDL mode. The WSDL file shows entities with nillable properties which correctly don't show up on response when they're null.

Unfortunately I need to use these properties even if they are null, but calling them generates a property not found notice in php.

So far I found three feasible solutions:

1. modify WSDL
2. check every nullable property with isset
3. check object against wsdl property to add missing properties as null properties.

So I was wondering if there is a standard and best practice solution available, let alone that modifying wsdl file is not feasible and I don't like checking every single property with isset.