Exhaustive whens without else and 'Nothing' as the result are considered 'implicit exhaustive'

compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumStatement.kt

@@ -13,8 +13,8 @@ public enum J {
 // FILE: K.kt
 
 fun foo(): Int {
-    when (<!WHEN_ENUM_CAN_BE_NULL_IN_JAVA!>J.create()<!>) {
+    <!DEBUG_INFO_IMPLICIT_EXHAUSTIVE!>when (<!WHEN_ENUM_CAN_BE_NULL_IN_JAVA!>J.create()<!>) {
         J.A -> return 1
         J.B -> return 2
-    }
+    }<!>
 }