internal RecipientInfoCollection(ICollection <RecipientInfo> recipientInfos)
 {
     _recipientInfos = new RecipientInfo[recipientInfos.Count];
     recipientInfos.CopyTo(_recipientInfos, 0);
 }
 internal RecipientInfoCollection(RecipientInfo recipientInfo)
 {
     _recipientInfos = new RecipientInfo[] { recipientInfo };
 }