Failed schema validation after insert with sdk's becuase of null value

Hi,
In relation to this thread, what would be the best recommended way to have a null value in an object relationship?

For instance, I have an object as follows:

public class Template : RealmObject
{
    [PrimaryKey]
    [MapTo("_id")]
    public int TemplateId { get; set; }
    public string TemplateDescription { get; set; }
    public Department Department { get; set; }
    public Example Example{ get; set; }
}

Where Department and Example are Realm objects.

When this is inserted into the realm by my .Net app, the entry in the MongoDB is as follows:

{
    "_id":{"$numberLong":"123"},"
    _partitionKey":"key",
    "Example":null,
    "Department":null,
    "TemplateDescription":"Example"
}

This fails validation because of the null values of Department and Example even though it still syncs with the app.

How do you suggest I implement this as you can’t create a default Realm Object to use in a relationship?

Many Thanks