Within a Groovy script I have the code:

```
if(payload != null && payload['result'] != null) {
    params ['result'] = payload['result']
}

```

The Payload received before coming to the Groovy component is **org.mule.transport.NullPayload**, so when I validate "payload" being `null` in the "if", it doesn't detect that is a `null`, which is expected since that class is intended for that purpose in **Mule 3.7.3**, so then what is the best practice to validate an instance org.mule.transport.NullPayload as a `null` value?