SoapBody declares that the Locale is mandatory where it is optional in SOAP 1.1

There's a nullability problem in `SoapBody` and its hierarchy. A `Locale` is not requires with Soap 1.1 but it became mandatory with SOAP 1.2.

There isn't a great way to deal with this, we'll have to declare that the locale can be removed and fail in 1.2 if it is not provided.