OpenHashMap doesn't work with more than 12M items

  test("support for more than 12M items") {
    val cnt = 12000000 // 12M
    val map = new OpenHashMap[Int, Int](cnt)
    for (i <- 0 until cnt) {
      map(i) = 1
    }
    val numInvalidValues = map.iterator.count(_._2 == 0)
    assertResult(0)(numInvalidValues)
  }