Installment Model with MongoDB Serialization attributes

Installment.cs

 [BsonIgnoreExtraElements]
    public class Installment : AggregateRoot
    {
        [BsonId, BsonRepresentation(BsonType.ObjectId)]
        public string Id { get; protected set; }

        [BsonRequired]
        public string Title { get; protected set; }

        public string Description { get; protected set; }

        [BsonRequired]
        public uint InstallmentFrequencyInDays { get; protected set; }

        [BsonRequired]
        public decimal DownPayment { get; protected set; }

        [BsonRequired]
        public uint TotalInstallments { get; protected set; }

        public Installment(string id, string title, string description, uint installmentFrequencyDays, decimal downPayment, uint totalInstallments)
        {
            Id = id;
            Title = title;
            Description = description;
            InstallmentFrequencyInDays = installmentFrequencyDays;
            DownPayment = downPayment;
            TotalInstallments = totalInstallments;
            Id = Guid.NewGuid().ToString();
        }

    }