Make it possible to use 'default value' in action creatioin time for 'ForEach' action

[dakusui]

I want to be able to do this.

  @PerformWith(Test.class)
  public Action composeSingleLoop2() {
    return sequential(
        simple("print hello", () -> System.out.println("hello")),
        forEachOf(
            asList("A", "B", "C")
        ).withDefault(
            "unknown"
        ).concurrently(
        ).perform(
            (Context $, DataHolder<String> value) -> {
              String v = value.isPresent() ?
                  value.get() :
                  String.format("(%s)", value.get());
              return $.sequential(
                  $.simple("print the given value(1st time)", () -> System.out.println(v)),
                  $.simple("print the given value(2nd time)", () -> System.out.println(v)),
                  $.sleep(2, MICROSECONDS)
              );
            }
        ),
        simple("print bye", () -> System.out.println("bye"))
    );
  }

[dakusui]

The value of this enhancement became unclear. Closing this for now.