public class addressModel
{
    public string street {get;set;}
    public string number {get;set;}
    public string state {get;set;}
}

public class contactModel
{
    public string firstName {get;set;}
    public string lastName {get;set;}
    public addressModel address {get;set;}
}

[MetadataType(typeof(driverMetadata))]
public class driverModel : contactModel
{

}

public class driverMetadata
{
    [Required]
    public addressModel address {get;set;}
}