[Feature Request]:[dotnet] Graph constructor should consider the case where transitions' value is null

[JeffreySu]

Is your feature request related to a problem? Please describe.

Graph constructor should consider the case where transitions' value is null

List.AddRange(transitions); not support a null param.

Describe the solution you'd like

change to:

    public Graph()
    {
    }

    public Graph(IEnumerable<Transition> transitions)
    {
        if (transitions != null)
        {
            this.transitions.AddRange(transitions);
        }

Additional context

No response