Converting an UUID to an MongoDB ObjectId by discarding a few insignificant bits

UUIDToObjectId.scala

object UUIDToObjectId {
  def uuidToObjectId(uuid: UUID): ObjectId = {
    import java.util.UUID
    import org.bson.types.ObjectId

    val b = java.nio.ByteBuffer.allocate(12)
    b.putLong(uuid.getMostSignificantBits)
    b.putInt((uuid.getLeastSignificantBits >> 16).intValue)
    new ObjectId(b.array())
  }
}