KeyInfo
Key information. 
                using Azure.Core;
using Azure.Storage.Common;
using System.Xml;
namespace Azure.Storage.Blobs.Models
{
    internal class KeyInfo : IXmlSerializable
    {
        public string Start { get; set; }
        public string Expiry { get; }
        public KeyInfo(string expiry)
        {
            Argument.AssertNotNull(expiry, "expiry");
            Expiry = expiry;
        }
        internal KeyInfo(string start, string expiry)
        {
            Start = start;
            Expiry = expiry;
        }
        void IXmlSerializable.Write(XmlWriter writer, string nameHint)
        {
            writer.WriteStartElement(nameHint ?? "KeyInfo");
            if (Optional.IsDefined(Start)) {
                writer.WriteStartElement("Start");
                writer.WriteValue(Start);
                writer.WriteEndElement();
            }
            writer.WriteStartElement("Expiry");
            writer.WriteValue(Expiry);
            writer.WriteEndElement();
            writer.WriteEndElement();
        }
    }
}