public List <string> this[string headerName]
        {
            get
            {
                return(Headers[HeaderHelpers.LookupComapactHeader(headerName)]);
            }

            set
            {
                Headers[HeaderHelpers.LookupComapactHeader(headerName)] = value;
            }
        }
 internal bool ContainsKey(string headerName)
 {
     return(Headers.ContainsKey(HeaderHelpers.LookupComapactHeader(headerName)));
 }