public PackageIdentifier(Guid id, VersionIdentifier version, double packageCostPrice, double packageRecommendedPrice)
 {
     Id = id;
     Version = version;
     PackageCostPrice = packageCostPrice;
     PackageRecommendedPrice = packageRecommendedPrice;
 }
 public PackageIdentifierBuilder WithVersion(VersionIdentifier version)
 {
     this.version = version;
     return this;
 }
 protected bool Equals(VersionIdentifier other)
 {
     return Number == other.Number && Date.Equals(other.Date);
 }
   public ContractIdentifier(Guid id, VersionIdentifier version)
 {
     Id = id;
     Version = version;
 }