diff --git a/jdk/src/share/classes/java/util/stream/Collectors.java b/jdk/src/share/classes/java/util/stream/Collectors.java
index 27c7c83ead4..bdbd8ad0774 100644
--- a/jdk/src/share/classes/java/util/stream/Collectors.java
+++ b/jdk/src/share/classes/java/util/stream/Collectors.java
@@ -137,6 +137,11 @@ public final class Collectors {
         return (u,v) -> { throw new IllegalStateException(String.format("Duplicate key %s", u)); };
     }
 
+    @SuppressWarnings("unchecked")
+    private static <I, R> Function<I, R> castingIdentity() {
+        return i -> (R) i;
+    }
+
     /**
      * Simple implementation class for {@code Collector}.
      *
@@ -166,7 +171,7 @@ public final class Collectors {
                       BiConsumer<A, T> accumulator,
                       BinaryOperator<A> combiner,
                       Set<Characteristics> characteristics) {
-            this(supplier, accumulator, combiner, i -> (R) i, characteristics);
+            this(supplier, accumulator, combiner, castingIdentity(), characteristics);
         }
 
         @Override
@@ -209,7 +214,7 @@ public final class Collectors {
      */
     public static <T, C extends Collection<T>>
     Collector<T, ?, C> toCollection(Supplier<C> collectionFactory) {
-        return new CollectorImpl<>(collectionFactory, Collection::add,
+        return new CollectorImpl<>(collectionFactory, Collection<T>::add,
                                    (r1, r2) -> { r1.addAll(r2); return r1; },
                                    CH_ID);
     }
@@ -1046,30 +1051,23 @@ public final class Collectors {
     public static <T, D, A>
     Collector<T, ?, Map<Boolean, D>> partitioningBy(Predicate<? super T> predicate,
                                                     Collector<? super T, A, D> downstream) {
-        @SuppressWarnings("unchecked")
-        BiConsumer<D, ? super T> downstreamAccumulator = (BiConsumer<D, ? super T>) downstream.accumulator();
-        BiConsumer<Map<Boolean, A>, T> accumulator = (result, t) -> {
-            Partition<D> asPartition = ((Partition<D>) result);
-            downstreamAccumulator.accept(predicate.test(t) ? asPartition.forTrue : asPartition.forFalse, t);
-        };
+        BiConsumer<A, ? super T> downstreamAccumulator = downstream.accumulator();
+        BiConsumer<Partition<A>, T> accumulator = (result, t) ->
+                downstreamAccumulator.accept(predicate.test(t) ? result.forTrue : result.forFalse, t);
         BinaryOperator<A> op = downstream.combiner();
-        BinaryOperator<Map<Boolean, A>> merger = (m1, m2) -> {
-            Partition<A> left = (Partition<A>) m1;
-            Partition<A> right = (Partition<A>) m2;
-            return new Partition<>(op.apply(left.forTrue, right.forTrue),
-                                   op.apply(left.forFalse, right.forFalse));
-        };
-        Supplier<Map<Boolean, A>> supplier = () -> new Partition<>(downstream.supplier().get(),
-                                                                   downstream.supplier().get());
+        BinaryOperator<Partition<A>> merger = (left, right) ->
+                new Partition<>(op.apply(left.forTrue, right.forTrue),
+                                op.apply(left.forFalse, right.forFalse));
+        Supplier<Partition<A>> supplier = () ->
+                new Partition<>(downstream.supplier().get(),
+                                downstream.supplier().get());
         if (downstream.characteristics().contains(Collector.Characteristics.IDENTITY_FINISH)) {
             return new CollectorImpl<>(supplier, accumulator, merger, CH_ID);
         }
         else {
-            Function<Map<Boolean, A>, Map<Boolean, D>> finisher = (Map<Boolean, A> par) -> {
-                Partition<A> asAPartition = (Partition<A>) par;
-                return new Partition<>(downstream.finisher().apply(asAPartition.forTrue),
-                                       downstream.finisher().apply(asAPartition.forFalse));
-            };
+            Function<Partition<A>, Map<Boolean, D>> finisher = par ->
+                    new Partition<>(downstream.finisher().apply(par.forTrue),
+                                    downstream.finisher().apply(par.forFalse));
             return new CollectorImpl<>(supplier, accumulator, merger, finisher, CH_NOID);
         }
     }
diff --git a/jdk/src/share/classes/java/util/stream/DistinctOps.java b/jdk/src/share/classes/java/util/stream/DistinctOps.java
index 69d231f88f5..1c4dfee5d67 100644
--- a/jdk/src/share/classes/java/util/stream/DistinctOps.java
+++ b/jdk/src/share/classes/java/util/stream/DistinctOps.java
@@ -101,7 +101,7 @@ final class DistinctOps {
                 if (StreamOpFlag.DISTINCT.isKnown(flags)) {
                     return sink;
                 } else if (StreamOpFlag.SORTED.isKnown(flags)) {
-                    return new Sink.ChainedReference<T>(sink) {
+                    return new Sink.ChainedReference<T, T>(sink) {
                         boolean seenNull;
                         T lastSeen;
 
@@ -132,7 +132,7 @@ final class DistinctOps {
                         }
                     };
                 } else {
-                    return new Sink.ChainedReference<T>(sink) {
+                    return new Sink.ChainedReference<T, T>(sink) {
                         Set<T> seen;
 
                         @Override
diff --git a/jdk/src/share/classes/java/util/stream/DoublePipeline.java b/jdk/src/share/classes/java/util/stream/DoublePipeline.java
index 44c8ff0f5e7..f894fa0abb9 100644
--- a/jdk/src/share/classes/java/util/stream/DoublePipeline.java
+++ b/jdk/src/share/classes/java/util/stream/DoublePipeline.java
@@ -191,7 +191,7 @@ abstract class DoublePipeline<E_IN>
                                        StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Double> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedDouble(sink) {
+                return new Sink.ChainedDouble<Double>(sink) {
                     @Override
                     public void accept(double t) {
                         downstream.accept(mapper.applyAsDouble(t));
@@ -208,9 +208,8 @@ abstract class DoublePipeline<E_IN>
                                                             StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Double> opWrapSink(int flags, Sink<U> sink) {
-                return new Sink.ChainedDouble(sink) {
+                return new Sink.ChainedDouble<U>(sink) {
                     @Override
-                    @SuppressWarnings("unchecked")
                     public void accept(double t) {
                         downstream.accept(mapper.apply(t));
                     }
@@ -226,7 +225,7 @@ abstract class DoublePipeline<E_IN>
                                                    StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Double> opWrapSink(int flags, Sink<Integer> sink) {
-                return new Sink.ChainedDouble(sink) {
+                return new Sink.ChainedDouble<Integer>(sink) {
                     @Override
                     public void accept(double t) {
                         downstream.accept(mapper.applyAsInt(t));
@@ -243,7 +242,7 @@ abstract class DoublePipeline<E_IN>
                                                     StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Double> opWrapSink(int flags, Sink<Long> sink) {
-                return new Sink.ChainedDouble(sink) {
+                return new Sink.ChainedDouble<Long>(sink) {
                     @Override
                     public void accept(double t) {
                         downstream.accept(mapper.applyAsLong(t));
@@ -259,7 +258,7 @@ abstract class DoublePipeline<E_IN>
                                         StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<Double> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedDouble(sink) {
+                return new Sink.ChainedDouble<Double>(sink) {
                     @Override
                     public void begin(long size) {
                         downstream.begin(-1);
@@ -296,7 +295,7 @@ abstract class DoublePipeline<E_IN>
                                        StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<Double> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedDouble(sink) {
+                return new Sink.ChainedDouble<Double>(sink) {
                     @Override
                     public void begin(long size) {
                         downstream.begin(-1);
@@ -319,7 +318,7 @@ abstract class DoublePipeline<E_IN>
                                        0) {
             @Override
             Sink<Double> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedDouble(sink) {
+                return new Sink.ChainedDouble<Double>(sink) {
                     @Override
                     public void accept(double t) {
                         consumer.accept(t);
diff --git a/jdk/src/share/classes/java/util/stream/IntPipeline.java b/jdk/src/share/classes/java/util/stream/IntPipeline.java
index d380e4a3bf5..f7dc79317d3 100644
--- a/jdk/src/share/classes/java/util/stream/IntPipeline.java
+++ b/jdk/src/share/classes/java/util/stream/IntPipeline.java
@@ -189,9 +189,8 @@ abstract class IntPipeline<E_IN>
                                                      StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Integer> opWrapSink(int flags, Sink<Long> sink) {
-                return new Sink.ChainedInt(sink) {
+                return new Sink.ChainedInt<Long>(sink) {
                     @Override
-                    @SuppressWarnings("unchecked")
                     public void accept(int t) {
                         downstream.accept((long) t);
                     }
@@ -206,9 +205,8 @@ abstract class IntPipeline<E_IN>
                                                        StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Integer> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedInt(sink) {
+                return new Sink.ChainedInt<Double>(sink) {
                     @Override
-                    @SuppressWarnings("unchecked")
                     public void accept(int t) {
                         downstream.accept((double) t);
                     }
@@ -229,7 +227,7 @@ abstract class IntPipeline<E_IN>
                                         StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Integer> opWrapSink(int flags, Sink<Integer> sink) {
-                return new Sink.ChainedInt(sink) {
+                return new Sink.ChainedInt<Integer>(sink) {
                     @Override
                     public void accept(int t) {
                         downstream.accept(mapper.applyAsInt(t));
@@ -246,9 +244,8 @@ abstract class IntPipeline<E_IN>
                                                              StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Integer> opWrapSink(int flags, Sink<U> sink) {
-                return new Sink.ChainedInt(sink) {
+                return new Sink.ChainedInt<U>(sink) {
                     @Override
-                    @SuppressWarnings("unchecked")
                     public void accept(int t) {
                         downstream.accept(mapper.apply(t));
                     }
@@ -264,7 +261,7 @@ abstract class IntPipeline<E_IN>
                                                      StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Integer> opWrapSink(int flags, Sink<Long> sink) {
-                return new Sink.ChainedInt(sink) {
+                return new Sink.ChainedInt<Long>(sink) {
                     @Override
                     public void accept(int t) {
                         downstream.accept(mapper.applyAsLong(t));
@@ -281,7 +278,7 @@ abstract class IntPipeline<E_IN>
                                                        StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Integer> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedInt(sink) {
+                return new Sink.ChainedInt<Double>(sink) {
                     @Override
                     public void accept(int t) {
                         downstream.accept(mapper.applyAsDouble(t));
@@ -297,7 +294,7 @@ abstract class IntPipeline<E_IN>
                                         StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<Integer> opWrapSink(int flags, Sink<Integer> sink) {
-                return new Sink.ChainedInt(sink) {
+                return new Sink.ChainedInt<Integer>(sink) {
                     @Override
                     public void begin(long size) {
                         downstream.begin(-1);
@@ -334,7 +331,7 @@ abstract class IntPipeline<E_IN>
                                         StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<Integer> opWrapSink(int flags, Sink<Integer> sink) {
-                return new Sink.ChainedInt(sink) {
+                return new Sink.ChainedInt<Integer>(sink) {
                     @Override
                     public void begin(long size) {
                         downstream.begin(-1);
@@ -357,7 +354,7 @@ abstract class IntPipeline<E_IN>
                                         0) {
             @Override
             Sink<Integer> opWrapSink(int flags, Sink<Integer> sink) {
-                return new Sink.ChainedInt(sink) {
+                return new Sink.ChainedInt<Integer>(sink) {
                     @Override
                     public void accept(int t) {
                         consumer.accept(t);
diff --git a/jdk/src/share/classes/java/util/stream/LongPipeline.java b/jdk/src/share/classes/java/util/stream/LongPipeline.java
index 083f7bb8b2b..3c199feab59 100644
--- a/jdk/src/share/classes/java/util/stream/LongPipeline.java
+++ b/jdk/src/share/classes/java/util/stream/LongPipeline.java
@@ -186,7 +186,7 @@ abstract class LongPipeline<E_IN>
                                                     StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Long> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedLong(sink) {
+                return new Sink.ChainedLong<Double>(sink) {
                     @Override
                     public void accept(long t) {
                         downstream.accept((double) t);
@@ -208,9 +208,8 @@ abstract class LongPipeline<E_IN>
                                      StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
-                return new Sink.ChainedLong(sink) {
+                return new Sink.ChainedLong<Long>(sink) {
                     @Override
-                    @SuppressWarnings("unchecked")
                     public void accept(long t) {
                         downstream.accept(mapper.applyAsLong(t));
                     }
@@ -226,9 +225,8 @@ abstract class LongPipeline<E_IN>
                                                           StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Long> opWrapSink(int flags, Sink<U> sink) {
-                return new Sink.ChainedLong(sink) {
+                return new Sink.ChainedLong<U>(sink) {
                     @Override
-                    @SuppressWarnings("unchecked")
                     public void accept(long t) {
                         downstream.accept(mapper.apply(t));
                     }
@@ -244,9 +242,8 @@ abstract class LongPipeline<E_IN>
                                                  StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Long> opWrapSink(int flags, Sink<Integer> sink) {
-                return new Sink.ChainedLong(sink) {
+                return new Sink.ChainedLong<Integer>(sink) {
                     @Override
-                    @SuppressWarnings("unchecked")
                     public void accept(long t) {
                         downstream.accept(mapper.applyAsInt(t));
                     }
@@ -262,7 +259,7 @@ abstract class LongPipeline<E_IN>
                                                     StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<Long> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedLong(sink) {
+                return new Sink.ChainedLong<Double>(sink) {
                     @Override
                     public void accept(long t) {
                         downstream.accept(mapper.applyAsDouble(t));
@@ -278,7 +275,7 @@ abstract class LongPipeline<E_IN>
                                      StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
-                return new Sink.ChainedLong(sink) {
+                return new Sink.ChainedLong<Long>(sink) {
                     @Override
                     public void begin(long size) {
                         downstream.begin(-1);
@@ -315,7 +312,7 @@ abstract class LongPipeline<E_IN>
                                      StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
-                return new Sink.ChainedLong(sink) {
+                return new Sink.ChainedLong<Long>(sink) {
                     @Override
                     public void begin(long size) {
                         downstream.begin(-1);
@@ -338,7 +335,7 @@ abstract class LongPipeline<E_IN>
                                      0) {
             @Override
             Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
-                return new Sink.ChainedLong(sink) {
+                return new Sink.ChainedLong<Long>(sink) {
                     @Override
                     public void accept(long t) {
                         consumer.accept(t);
diff --git a/jdk/src/share/classes/java/util/stream/ReferencePipeline.java b/jdk/src/share/classes/java/util/stream/ReferencePipeline.java
index c201950d88c..1fffff48b18 100644
--- a/jdk/src/share/classes/java/util/stream/ReferencePipeline.java
+++ b/jdk/src/share/classes/java/util/stream/ReferencePipeline.java
@@ -163,17 +163,16 @@ abstract class ReferencePipeline<P_IN, P_OUT>
                                      StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<P_OUT> opWrapSink(int flags, Sink<P_OUT> sink) {
-                return new Sink.ChainedReference<P_OUT>(sink) {
+                return new Sink.ChainedReference<P_OUT, P_OUT>(sink) {
                     @Override
                     public void begin(long size) {
                         downstream.begin(-1);
                     }
 
                     @Override
-                    @SuppressWarnings("unchecked")
                     public void accept(P_OUT u) {
                         if (predicate.test(u))
-                            downstream.accept((Object) u);
+                            downstream.accept(u);
                     }
                 };
             }
@@ -188,7 +187,7 @@ abstract class ReferencePipeline<P_IN, P_OUT>
                                      StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<P_OUT> opWrapSink(int flags, Sink<R> sink) {
-                return new Sink.ChainedReference<P_OUT>(sink) {
+                return new Sink.ChainedReference<P_OUT, R>(sink) {
                     @Override
                     public void accept(P_OUT u) {
                         downstream.accept(mapper.apply(u));
@@ -205,7 +204,7 @@ abstract class ReferencePipeline<P_IN, P_OUT>
                                               StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<P_OUT> opWrapSink(int flags, Sink<Integer> sink) {
-                return new Sink.ChainedReference<P_OUT>(sink) {
+                return new Sink.ChainedReference<P_OUT, Integer>(sink) {
                     @Override
                     public void accept(P_OUT u) {
                         downstream.accept(mapper.applyAsInt(u));
@@ -222,7 +221,7 @@ abstract class ReferencePipeline<P_IN, P_OUT>
                                       StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<P_OUT> opWrapSink(int flags, Sink<Long> sink) {
-                return new Sink.ChainedReference<P_OUT>(sink) {
+                return new Sink.ChainedReference<P_OUT, Long>(sink) {
                     @Override
                     public void accept(P_OUT u) {
                         downstream.accept(mapper.applyAsLong(u));
@@ -239,7 +238,7 @@ abstract class ReferencePipeline<P_IN, P_OUT>
                                         StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {
             @Override
             Sink<P_OUT> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedReference<P_OUT>(sink) {
+                return new Sink.ChainedReference<P_OUT, Double>(sink) {
                     @Override
                     public void accept(P_OUT u) {
                         downstream.accept(mapper.applyAsDouble(u));
@@ -257,14 +256,13 @@ abstract class ReferencePipeline<P_IN, P_OUT>
                                      StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<P_OUT> opWrapSink(int flags, Sink<R> sink) {
-                return new Sink.ChainedReference<P_OUT>(sink) {
+                return new Sink.ChainedReference<P_OUT, R>(sink) {
                     @Override
                     public void begin(long size) {
                         downstream.begin(-1);
                     }
 
                     @Override
-                    @SuppressWarnings("unchecked")
                     public void accept(P_OUT u) {
                         // We can do better that this too; optimize for depth=0 case and just grab spliterator and forEach it
                         Stream<? extends R> result = mapper.apply(u);
@@ -284,7 +282,7 @@ abstract class ReferencePipeline<P_IN, P_OUT>
                                               StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<P_OUT> opWrapSink(int flags, Sink<Integer> sink) {
-                return new Sink.ChainedReference<P_OUT>(sink) {
+                return new Sink.ChainedReference<P_OUT, Integer>(sink) {
                     IntConsumer downstreamAsInt = downstream::accept;
                     @Override
                     public void begin(long size) {
@@ -311,7 +309,7 @@ abstract class ReferencePipeline<P_IN, P_OUT>
                                                      StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<P_OUT> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedReference<P_OUT>(sink) {
+                return new Sink.ChainedReference<P_OUT, Double>(sink) {
                     DoubleConsumer downstreamAsDouble = downstream::accept;
                     @Override
                     public void begin(long size) {
@@ -338,7 +336,7 @@ abstract class ReferencePipeline<P_IN, P_OUT>
                                                    StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {
             @Override
             Sink<P_OUT> opWrapSink(int flags, Sink<Long> sink) {
-                return new Sink.ChainedReference<P_OUT>(sink) {
+                return new Sink.ChainedReference<P_OUT, Long>(sink) {
                     LongConsumer downstreamAsLong = downstream::accept;
                     @Override
                     public void begin(long size) {
@@ -364,9 +362,8 @@ abstract class ReferencePipeline<P_IN, P_OUT>
                                      0) {
             @Override
             Sink<P_OUT> opWrapSink(int flags, Sink<P_OUT> sink) {
-                return new Sink.ChainedReference<P_OUT>(sink) {
+                return new Sink.ChainedReference<P_OUT, P_OUT>(sink) {
                     @Override
-                    @SuppressWarnings("unchecked")
                     public void accept(P_OUT u) {
                         tee.accept(u);
                         downstream.accept(u);
@@ -495,6 +492,7 @@ abstract class ReferencePipeline<P_IN, P_OUT>
     }
 
     @Override
+    @SuppressWarnings("unchecked")
     public final <R, A> R collect(Collector<? super P_OUT, A, ? extends R> collector) {
         A container;
         if (isParallel()
diff --git a/jdk/src/share/classes/java/util/stream/Sink.java b/jdk/src/share/classes/java/util/stream/Sink.java
index 987d0e9efa7..d2a366df16e 100644
--- a/jdk/src/share/classes/java/util/stream/Sink.java
+++ b/jdk/src/share/classes/java/util/stream/Sink.java
@@ -241,11 +241,10 @@ interface Sink<T> extends Consumer<T> {
      * implementation of the {@code accept()} method must call the correct
      * {@code accept()} method on the downstream {@code Sink}.
      */
-    static abstract class ChainedReference<T> implements Sink<T> {
-        @SuppressWarnings("rawtypes")
-        protected final Sink downstream;
+    static abstract class ChainedReference<T, E_OUT> implements Sink<T> {
+        protected final Sink<? super E_OUT> downstream;
 
-        public ChainedReference(Sink downstream) {
+        public ChainedReference(Sink<? super E_OUT> downstream) {
             this.downstream = Objects.requireNonNull(downstream);
         }
 
@@ -274,11 +273,10 @@ interface Sink<T> extends Consumer<T> {
      * The implementation of the {@code accept()} method must call the correct
      * {@code accept()} method on the downstream {@code Sink}.
      */
-    static abstract class ChainedInt implements Sink.OfInt {
-        @SuppressWarnings("rawtypes")
-        protected final Sink downstream;
+    static abstract class ChainedInt<E_OUT> implements Sink.OfInt {
+        protected final Sink<? super E_OUT> downstream;
 
-        public ChainedInt(Sink downstream) {
+        public ChainedInt(Sink<? super E_OUT> downstream) {
             this.downstream = Objects.requireNonNull(downstream);
         }
 
@@ -307,11 +305,10 @@ interface Sink<T> extends Consumer<T> {
      * The implementation of the {@code accept()} method must call the correct
      * {@code accept()} method on the downstream {@code Sink}.
      */
-    static abstract class ChainedLong implements Sink.OfLong {
-        @SuppressWarnings("rawtypes")
-        protected final Sink downstream;
+    static abstract class ChainedLong<E_OUT> implements Sink.OfLong {
+        protected final Sink<? super E_OUT> downstream;
 
-        public ChainedLong(Sink downstream) {
+        public ChainedLong(Sink<? super E_OUT> downstream) {
             this.downstream = Objects.requireNonNull(downstream);
         }
 
@@ -340,11 +337,10 @@ interface Sink<T> extends Consumer<T> {
      * The implementation of the {@code accept()} method must call the correct
      * {@code accept()} method on the downstream {@code Sink}.
      */
-    static abstract class ChainedDouble implements Sink.OfDouble {
-        @SuppressWarnings("rawtypes")
-        protected final Sink downstream;
+    static abstract class ChainedDouble<E_OUT> implements Sink.OfDouble {
+        protected final Sink<? super E_OUT> downstream;
 
-        public ChainedDouble(Sink downstream) {
+        public ChainedDouble(Sink<? super E_OUT> downstream) {
             this.downstream = Objects.requireNonNull(downstream);
         }
 
diff --git a/jdk/src/share/classes/java/util/stream/SliceOps.java b/jdk/src/share/classes/java/util/stream/SliceOps.java
index 09e14f637f4..34d55309d2d 100644
--- a/jdk/src/share/classes/java/util/stream/SliceOps.java
+++ b/jdk/src/share/classes/java/util/stream/SliceOps.java
@@ -96,6 +96,11 @@ final class SliceOps {
         }
     }
 
+    @SuppressWarnings("unchecked")
+    private static <T> IntFunction<T[]> castingArray() {
+        return size -> (T[]) new Object[size];
+    }
+
     /**
      * Appends a "slice" operation to the provided stream.  The slice operation
      * may be may be skip-only, limit-only, or skip-and-limit.
@@ -107,12 +112,12 @@ final class SliceOps {
      *        is to be imposed
      */
     public static <T> Stream<T> makeRef(AbstractPipeline<?, T, ?> upstream,
-                                       long skip, long limit) {
+                                        long skip, long limit) {
         if (skip < 0)
             throw new IllegalArgumentException("Skip must be non-negative: " + skip);
 
-        return new ReferencePipeline.StatefulOp<T,T>(upstream, StreamShape.REFERENCE,
-                                                     flags(limit)) {
+        return new ReferencePipeline.StatefulOp<T, T>(upstream, StreamShape.REFERENCE,
+                                                      flags(limit)) {
             Spliterator<T> unorderedSkipLimitSpliterator(Spliterator<T> s,
                                                          long skip, long limit, long sizeIfKnown) {
                 if (skip <= sizeIfKnown) {
@@ -146,7 +151,7 @@ final class SliceOps {
                     //     cancellation will be more aggressive cancelling later tasks
                     //     if the target slice size has been reached from a given task,
                     //     cancellation should also clear local results if any
-                    return new SliceTask<>(this, helper, spliterator, i -> (T[]) new Object[i], skip, limit).
+                    return new SliceTask<>(this, helper, spliterator, castingArray(), skip, limit).
                             invoke().spliterator();
                 }
             }
@@ -182,7 +187,7 @@ final class SliceOps {
 
             @Override
             Sink<T> opWrapSink(int flags, Sink<T> sink) {
-                return new Sink.ChainedReference<T>(sink) {
+                return new Sink.ChainedReference<T, T>(sink) {
                     long n = skip;
                     long m = limit >= 0 ? limit : Long.MAX_VALUE;
 
@@ -291,7 +296,7 @@ final class SliceOps {
 
             @Override
             Sink<Integer> opWrapSink(int flags, Sink<Integer> sink) {
-                return new Sink.ChainedInt(sink) {
+                return new Sink.ChainedInt<Integer>(sink) {
                     long n = skip;
                     long m = limit >= 0 ? limit : Long.MAX_VALUE;
 
@@ -400,7 +405,7 @@ final class SliceOps {
 
             @Override
             Sink<Long> opWrapSink(int flags, Sink<Long> sink) {
-                return new Sink.ChainedLong(sink) {
+                return new Sink.ChainedLong<Long>(sink) {
                     long n = skip;
                     long m = limit >= 0 ? limit : Long.MAX_VALUE;
 
@@ -509,7 +514,7 @@ final class SliceOps {
 
             @Override
             Sink<Double> opWrapSink(int flags, Sink<Double> sink) {
-                return new Sink.ChainedDouble(sink) {
+                return new Sink.ChainedDouble<Double>(sink) {
                     long n = skip;
                     long m = limit >= 0 ? limit : Long.MAX_VALUE;
 
@@ -560,13 +565,13 @@ final class SliceOps {
 
         private volatile boolean completed;
 
-        SliceTask(AbstractPipeline<?, P_OUT, ?> op,
+        SliceTask(AbstractPipeline<P_OUT, P_OUT, ?> op,
                   PipelineHelper<P_OUT> helper,
                   Spliterator<P_IN> spliterator,
                   IntFunction<P_OUT[]> generator,
                   long offset, long size) {
             super(helper, spliterator);
-            this.op = (AbstractPipeline<P_OUT, P_OUT, ?>) op;
+            this.op = op;
             this.generator = generator;
             this.targetOffset = offset;
             this.targetSize = size;
diff --git a/jdk/src/share/classes/java/util/stream/SortedOps.java b/jdk/src/share/classes/java/util/stream/SortedOps.java
index 047479a645d..9df65e352e2 100644
--- a/jdk/src/share/classes/java/util/stream/SortedOps.java
+++ b/jdk/src/share/classes/java/util/stream/SortedOps.java
@@ -129,7 +129,7 @@ final class SortedOps {
         }
 
         @Override
-        public Sink<T> opWrapSink(int flags, Sink sink) {
+        public Sink<T> opWrapSink(int flags, Sink<T> sink) {
             Objects.requireNonNull(sink);
 
             // If the input is already naturally sorted and this operation
@@ -280,12 +280,12 @@ final class SortedOps {
     /**
      * {@link ForkJoinTask} for implementing sort on SIZED reference streams.
      */
-    private static final class SizedRefSortingSink<T> extends Sink.ChainedReference<T> {
+    private static final class SizedRefSortingSink<T> extends Sink.ChainedReference<T, T> {
         private final Comparator<? super T> comparator;
         private T[] array;
         private int offset;
 
-        SizedRefSortingSink(Sink<T> sink, Comparator<? super T> comparator) {
+        SizedRefSortingSink(Sink<? super T> sink, Comparator<? super T> comparator) {
             super(sink);
             this.comparator = comparator;
         }
@@ -320,11 +320,11 @@ final class SortedOps {
     /**
      * {@link Sink} for implementing sort on reference streams.
      */
-    private static final class RefSortingSink<T> extends Sink.ChainedReference<T> {
+    private static final class RefSortingSink<T> extends Sink.ChainedReference<T, T> {
         private final Comparator<? super T> comparator;
         private ArrayList<T> list;
 
-        RefSortingSink(Sink<T> sink, Comparator<? super T> comparator) {
+        RefSortingSink(Sink<? super T> sink, Comparator<? super T> comparator) {
             super(sink);
             this.comparator = comparator;
         }
@@ -352,11 +352,11 @@ final class SortedOps {
     /**
      * {@link Sink} for implementing sort on SIZED int streams.
      */
-    private static final class SizedIntSortingSink extends Sink.ChainedInt {
+    private static final class SizedIntSortingSink extends Sink.ChainedInt<Integer> {
         private int[] array;
         private int offset;
 
-        SizedIntSortingSink(Sink downstream) {
+        SizedIntSortingSink(Sink<? super Integer> downstream) {
             super(downstream);
         }
 
@@ -386,10 +386,10 @@ final class SortedOps {
     /**
      * {@link Sink} for implementing sort on int streams.
      */
-    private static final class IntSortingSink extends Sink.ChainedInt {
+    private static final class IntSortingSink extends Sink.ChainedInt<Integer> {
         private SpinedBuffer.OfInt b;
 
-        IntSortingSink(Sink sink) {
+        IntSortingSink(Sink<? super Integer> sink) {
             super(sink);
         }
 
@@ -417,11 +417,11 @@ final class SortedOps {
     /**
      * {@link Sink} for implementing sort on SIZED long streams.
      */
-    private static final class SizedLongSortingSink extends Sink.ChainedLong {
+    private static final class SizedLongSortingSink extends Sink.ChainedLong<Long> {
         private long[] array;
         private int offset;
 
-        SizedLongSortingSink(Sink downstream) {
+        SizedLongSortingSink(Sink<? super Long> downstream) {
             super(downstream);
         }
 
@@ -451,10 +451,10 @@ final class SortedOps {
     /**
      * {@link Sink} for implementing sort on long streams.
      */
-    private static final class LongSortingSink extends Sink.ChainedLong {
+    private static final class LongSortingSink extends Sink.ChainedLong<Long> {
         private SpinedBuffer.OfLong b;
 
-        LongSortingSink(Sink sink) {
+        LongSortingSink(Sink<? super Long> sink) {
             super(sink);
         }
 
@@ -482,11 +482,11 @@ final class SortedOps {
     /**
      * {@link Sink} for implementing sort on SIZED double streams.
      */
-    private static final class SizedDoubleSortingSink extends Sink.ChainedDouble {
+    private static final class SizedDoubleSortingSink extends Sink.ChainedDouble<Double> {
         private double[] array;
         private int offset;
 
-        SizedDoubleSortingSink(Sink downstream) {
+        SizedDoubleSortingSink(Sink<? super Double> downstream) {
             super(downstream);
         }
 
@@ -516,10 +516,10 @@ final class SortedOps {
     /**
      * {@link Sink} for implementing sort on double streams.
      */
-    private static final class DoubleSortingSink extends Sink.ChainedDouble {
+    private static final class DoubleSortingSink extends Sink.ChainedDouble<Double> {
         private SpinedBuffer.OfDouble b;
 
-        DoubleSortingSink(Sink sink) {
+        DoubleSortingSink(Sink<? super Double> sink) {
             super(sink);
         }