How to copy List in dart without old reference?

class MyModal {
  int myField1;
  String myField2;
  List<MyModal> adjacentNodes;
  MyModal(this.myField1,this.myField2);

  MyModal.clone(MyModal source) : 
      this.myField1 = source.myField1, 
      this.myField2 = source.myField2,
      this.adjacentNodes = source.adjacentNodes.map((item) => new MyModal.clone(item)).toList();
}

var secondList = originalList.map((item) => new MyModal.clone(item)).toList();

If a member of MyModal is of a non-primitive type like String, int, double, num, bool, then the clone() method needs to clone the instances references point to as well.

I think for your use case using immutable values is a better approach, for example with https://pub.dartlang.org/packages/built_value