val item1: String = ""
val item2: String? = getItem2()

val map = mapOf(1 to item1, 2 to item2) //only if item2 is not null

val map = if (item2 != null) mapOf(1 to item1, 2 to item2) else mapOf(1 to item1)

mapOf(1 to item1, 2 to item2)
   .filter {it.value != null}
   .map{ Pair(it.key, it.value!!)}

map.filterValues { it != null }
    .mapValues { it.value!! }

fun main() {
  val allItems = listOf(
      "",
      getItem2()
  )

  val map = allItems.filterNotNull().mapIndexed { index, el -> index to el }
}

fun getItem2(): String? {
  val rnd = Random.nextInt()
  if (rnd % 2 == 0) {
    return "Not null string"
  }
  return null
}