public virtual ReadOnlyMemory <byte> GenerateRandomBytes(int size)
        {
            var span = new Span <byte>(new byte[size]);

            RandomNumberGenerator.Fill(span);

            return(span.AsMemory());
        }
        public virtual ReadOnlyMemory <byte> GenerateRandomBytes(int size)
        {
            var arr  = new byte[size];
            var span = new Span <byte>(arr);

            RandomNumberGenerator.Create().GetBytes(arr);
            return(span.AsMemory());
        }