implicit abstract class problem

AbstractBase

package base;

import java.util.List;

public abstract class AbstractBase {
    abstract protected List getChildren();
}

BaseImplit

package base

import java.util

object BaseImplit {
  implicit class SBase[T <: AbstractBase](child: T) extends AbstractBase {

    protected def getChildren: util.List[_] = child.getChildren

    def apply = child.getChildren
  }
}

main

package com.github.notyy.retroboard.util
import base.AbstractBase
import scala.collection.JavaConverters._

class Child1 extends AbstractBase {
  protected def getChildren: java.util.List[String] = List("child1").asJava
}

class Child2 extends AbstractBase {
  def getChildren: java.util.List[String] = List("child2").asJava
}

object ImplicitTest extends App{
  import base.BaseImplit._

  println(new Child1().apply)
  println(new Child2().apply)
}

output is

[child1]
[child2]