How can I use fields of const-constructed objects in switch cases?

main.dart

class Property
{
  final String foo;

  const Property(String this.foo);
}

const Property MARGIN = const Property("margin");
const Property PADDING = const Property("padding");

void main()
{

Property someProperty = MARGIN;

switch(someProperty.foo)
{
  case MARGIN.foo:
    //doThis();
    break;
  case PADDING.foo:
    //doThis();
    break;
}

}