Map wrapper can easily return Some(null)

gistfile1.scala

import scala.collection.convert.Wrappers.JMapWrapper
import java.util.Collections

object MapTest extends App {

  val m = new JMapWrapper(Collections.synchronizedMap(new java.util.HashMap[String,String]))
 
  new Thread {
    override def run {
      while (true) {
        m += ("foo" -> "bar")
        m -= "foo"
      }
        
    }
  }.start()
  
  new Thread {
    override def run {
      while (true) {
        if (m.get("foo") == Some(null))
          println("got null")
      }        
    }
  }.start()
  
}