Extensions

public static void PerformAs<TOut>(this IEntity item, Action<TOut> perform) where TOut : class, IEntity
{
    var conversionResult = item as TOut;
    conversionResult.Perform(converted => perform(converted));
}


public static IEnumerable<T> OrEmptyIfNull<T>(this IEnumerable<T> source)
{
    return source ?? Enumerable.Empty<T>();
}


// Current
(owner as RetainedOrg).Perform(o => o.BusinessUnit.HasValue());
 
 // Extension
owner.PerformAs<RetainedOrg>(o => o.BusinessUnit.HasValue());