public async Task <bool> Handle(MoveInCommand message, CancellationToken cancellationToken)
{
// Add/Update the Buyer AggregateRoot
// DDD patterns comment: Add child entities and value-objects through the Order Aggregate-Root
// methods and constructor so validations, invariants and business logic
// make sure that consistency is preserved across the whole aggregate
Flat flat = new Flat(message.flatNo);
flat.MoveIn(message.List);
_flatRepository.Add(flat);
return(await _flatRepository
.SaveEntitiesAsync());
}