How to execute a private static method with optional parameters via reflection?
public class Foo {
    private static void Bar(string key = "") {
       // do stuff
    }
}

Foo.Bar()

Foo.Bar("")

var method = typeof(Foo).GetMethod("Bar", BindingFlags.Static | BindingFlags.NonPublic);

method.Invoke(obj: null, parameters: new object[] { "Test" });

foreach (ParameterInfo pi in method.GetParameters())
{
    if (pi.IsOptional)
    {
        Console.WriteLine(pi.Name + ": " + pi.DefaultValue);
    }
}

public class Foo
  {
    private static void Bar(string key = "undefined key", string value = "undefined value")
    {
      Console.WriteLine(string.Format("The key is '{0}'", key));
      Console.WriteLine(string.Format("The value is '{0}'", value));
    }
  }

MethodInfo mi = typeof(Foo).GetMethod("Bar", BindingFlags.NonPublic | BindingFlags.Static);
  ParameterInfo[] pis = mi.GetParameters();

  object[] parameters = new object[pis.Length];

  for (int i = 0; i < pis.Length; i++)
  {
    if (pis[i].IsOptional)
    {
      parameters[i] = pis[i].DefaultValue;
    }
  }

  mi.Invoke(null, parameters);

private static void Bar(int number, string key = "undefined key", string value = "undefined")

parameters[0] = "23"