ModelBuilder.GuidValueGenerator.GenerateValue C# (CSharp) Method

        protected override object GenerateValue(Type type, string referenceName, LinkedList<object> buildChain)
        {
            if (type == typeof(Guid))
            {
                return Guid.NewGuid();
            }

            // Weight the random distribution so that it is roughly 5 times more likely to get a new guid than a null
            var source = Generator.NextValue<double>(0, 5);

            Guid? value;

            if (source < 1)
            {
                value = null;
            }
            else
            {
                value = Guid.NewGuid();
            }

            return value;
        }
    }