Nullables feature request

Could the library start using nullables in the source code? Otherwise its really hard to know what is initialized and what not or you need to check everything.

For example:
```csharp
var container = new V1Container();
container.VolumeMounts.Add(new V1VolumeMount());
```
produces:
Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.