Void Parameter

Because of type erasure in Java, some methods cannot be overloaded

Consider:

class Foo {

   def add(v: Double) = App.Fail.toDo

   def add(v: Percent) = App.Fail.toDo

 }

Class Foo will not compile, because Percent is AnyVal with Double value, and it is erased to Double

The solution is to add a void parameter, which will not affect usage

class Foo {

   def add(v: Double) = App.Fail.toDo

   def add(v: Percent, V: \/ = \/) = App.Fail.toDo

 }