How to use Implicit optional for a delegate

Question

I want to use implicits for Dependency injection, in my code I want to provide a default implementation but I want to give the person who might use my Class to inject its own implementation but I can't figure out best way to do it.

General is something likes this

class ClassA {
   val something : ClassB = new ClassB()

   something.eventAdapter(new MyDefaultImplementation())
}

class MyDefaultImplementation(implicit specificImplementation: EventAdapter[EventA, EventB] = null) extends EventAdapter[EventA, EventB] {
    override def doSomething(event: EventA) : EventB = {
        if(specificImplementation != null) {
           specificImplementation.doSomething(event)
        } else {
           event match {
             case _ => new EventB()
           }
        }
    }
}

and if some other developer want to provide another implementation.

object OtherDeveloperImplementation {
    implicit val otherImplementation = OtherDeveloperImplementation()
}

class OtherDeveloperImplementation extends extends EventAdapter[EventA, EventB] {
    override def doSomething(event: EventA) : EventB = {
        convert(event)
    }
}

My dilemma is, I don't know what the other developer will call his class, so I can't make an import in 'ClassA' something like the following.

class ClassA {
   import OtherDeveloperImplementation._
   val something : ClassB = new ClassB()

   something.eventAdapter(new MyDefaultImplementation())
}

because I don't know how the developer name his class, how should I deal with this?

Thx for answers