eq null returns false for NewtypeWrapped

[kamilkloch]

Compare it with the wrapping via normal case class:

import monix.newtypes.{NewsubtypeWrapped, NewtypeWrapped}

import java.util.concurrent.atomic.AtomicReference

object NewTypeNull extends App {
  case class W1(value: String)

  type W2 = W2.Type
  object W2 extends NewtypeWrapped[String]

  type W3 = W3.Type
  object W3 extends NewsubtypeWrapped[String]

  val a1 = new AtomicReference[W1]()
  val a2 = new AtomicReference[W2]()
  val a3 = new AtomicReference[W3]()

  println(s"[a1.get(): ${a1.get()}], [a1.get() == null: ${a1.get() == null}], [a1.get() eq null: ${a1.get() eq null}]")
  println(s"[a2.get(): ${a2.get()}], [a2.get() == null: ${a2.get() == null}], [a2.get() eq null: ${a2.get() eq null}]")
  println(s"[a3.get(): ${a3.get()}], [a3.get() == null: ${a3.get() == null}], [a3.get() eq null: ${a3.get() eq null}]")
}

prints

[a1.get(): null], [a1.get() == null: true], [a1.get() eq null: true]
[a2.get(): null], [a2.get() == null: true], [a2.get() eq null: false]
[a3.get(): null], [a3.get() == null: true], [a3.get() eq null: true]