Minor. Use ArrayList instead of LinkedHashSet

Looks like there's no duplicates anyway

core/util.runtime/src/org/jetbrains/kotlin/utils/collections.kt

@@ -84,6 +84,13 @@ fun <T> Collection<T>.toReadOnlyList(): List<T> =
             else -> ArrayList(this)
         }
 
+fun <T> ArrayList<T>.compactIfPossible(): List<T> =
+        when (size) {
+            0 -> emptyList()
+            1 -> listOf(first())
+            else -> apply(ArrayList<T>::trimToSize)
+        }
+
 fun <T: Any> T?.singletonOrEmptyList(): List<T> =
         if (this != null) listOf(this) else emptyList()
 
@@ -92,4 +99,4 @@ fun <T> List<T>.indexOfFirst(startFrom: Int, predicate: (T) -> Boolean): Int {
         if (predicate(this[index])) return index
     }
     return -1
-}
+}