How to assign value in protected set declaration like creatorId in abp io .net

Question

I am using .net abp io. I have a problem to assign a protected set like creatorId. Below is the sample:

public virtual Guid? CreatorId { get; protected set; } My code in service :

var status = new rejectStatus()`
  {
   Id = query.Id,
   RejectDate = DateTime.Now,  
   CreatorId = query.CreatorId
};