Fix filterNotNull and mapNotNull for streams.

libraries/stdlib/src/generated/_Filtering.kt

@@ -561,7 +561,7 @@ public fun <T : Any> Iterable<T?>.filterNotNull(): List<T> {
  * Returns a stream containing all elements that are not null
  */
 public fun <T : Any> Stream<T?>.filterNotNull(): Stream<T> {
-    return FilteringStream(this, false, { it != null }) as Stream<T>
+    return FilteringStream(this, false, { it == null }) as Stream<T>
 }
 
 /**

libraries/stdlib/src/generated/_Mapping.kt

@@ -597,7 +597,7 @@ public inline fun <T : Any, R> Iterable<T?>.mapNotNull(transform: (T) -> R): Lis
  * Returns a stream containing the results of applying the given *transform* function to each non-null element of the original stream
  */
 public fun <T : Any, R> Stream<T?>.mapNotNull(transform: (T) -> R): Stream<R> {
-    return TransformingStream(FilteringStream(this, false, { it != null }) as Stream<T>, transform)
+    return TransformingStream(FilteringStream(this, false, { it == null }) as Stream<T>, transform)
 }
 
 /**

libraries/tools/kotlin-stdlib-gen/src/templates/Filtering.kt

@@ -305,7 +305,7 @@ fun filtering(): List<GenericFunction> {
         returns(Streams) { "Stream<T>" }
         body(Streams) {
             """
-            return FilteringStream(this, false, { it != null }) as Stream<T>
+            return FilteringStream(this, false, { it == null }) as Stream<T>
             """
         }
     }

libraries/tools/kotlin-stdlib-gen/src/templates/Mapping.kt

@@ -63,7 +63,7 @@ fun mapping(): List<GenericFunction> {
         inline(false, Streams)
         body(Streams) {
             """
-            return TransformingStream(FilteringStream(this, false, { it != null }) as Stream<T>, transform)
+            return TransformingStream(FilteringStream(this, false, { it == null }) as Stream<T>, transform)
             """
         }
     }