Add samples for mapNotNull, find, getOrNull functions

libraries/stdlib/samples/test/samples/collections/collections.kt

@@ -532,6 +532,15 @@ class Collections {
             assertPrints(numbers.map { it * it }, "[1, 4, 9]")
         }
 
+        @Sample
+        fun mapNotNull() {
+            val strings: List<String> = listOf("12a", "45", "", "3")
+            val ints: List<Int> = strings.mapNotNull { it.toIntOrNull() }
+
+            assertPrints(ints, "[45, 3]")
+            assertPrints(ints.sum(), "48")
+        }
+
         @Sample
         fun flatMap() {
             val list = listOf("123", "45")
@@ -770,6 +779,27 @@ class Collections {
             val emptyList = emptyList<Int>()
             assertPrints(emptyList.elementAtOrElse(0) { "no int" }, "no int")
         }
+
+        @Sample
+        fun find() {
+            val numbers = listOf(1, 2, 3, 4, 5, 6, 7)
+            val firstOdd = numbers.find { it % 2 != 0 }
+            val lastEven = numbers.findLast { it % 2 == 0 }
+
+            assertPrints(firstOdd, "1")
+            assertPrints(lastEven, "6")
+        }
+
+        @Sample
+        fun getOrNull() {
+            val list = listOf(1, 2, 3)
+            assertPrints(list.getOrNull(0), "1")
+            assertPrints(list.getOrNull(2), "3")
+            assertPrints(list.getOrNull(3), "null")
+
+            val emptyList = emptyList<Int>()
+            assertPrints(emptyList.getOrNull(0), "null")
+        }
     }
 
     class Sorting {

libraries/stdlib/samples/test/samples/collections/maps.kt

@@ -325,6 +325,14 @@ class Maps {
             assertPrints(map2, "{beverage=2.7$, meal=12.4$}")
         }
 
+        @Sample
+        fun mapNotNull() {
+            val map = mapOf("Alice" to 20, "Tom" to 13, "Bob" to 18)
+            val adults = map.mapNotNull { (name, age) -> name.takeIf { age >= 18 } }
+
+            assertPrints(adults, "[Alice, Bob]")
+        }
+
         @Sample
         fun mapToSortedMap() {
             val map = mapOf(Pair("c", 3), Pair("b", 2), Pair("d", 1))