RFR 8132097: Stream.generate should use a covariant Supplier as parameter

[Paul Sandoz]

Hi

Please review this compatible fix to Stream.generate to accept a covariant 
Supplier.

Paul.

diff -r 3e3ca9800322 src/java.base/share/classes/java/util/stream/Stream.java
--- a/src/java.base/share/classes/java/util/stream/Stream.java  Tue Nov 08 
15:37:20 2016 -0800
+++ b/src/java.base/share/classes/java/util/stream/Stream.java  Tue Nov 08 
16:36:51 2016 -0800
@@ -1327,7 +1327,7 @@
      * @param s the {@code Supplier} of generated elements
      * @return a new infinite sequential unordered {@code Stream}
      */
-    public static<T> Stream<T> generate(Supplier<T> s) {
+    public static<T> Stream<T> generate(Supplier<? extends T> s) {
         Objects.requireNonNull(s);
         return StreamSupport.stream(
                 new 
StreamSpliterators.InfiniteSupplyingSpliterator.OfRef<>(Long.MAX_VALUE, s), 
false);
diff -r 3e3ca9800322 
src/java.base/share/classes/java/util/stream/StreamSpliterators.java
--- a/src/java.base/share/classes/java/util/stream/StreamSpliterators.java      
Tue Nov 08 15:37:20 2016 -0800
+++ b/src/java.base/share/classes/java/util/stream/StreamSpliterators.java      
Tue Nov 08 16:36:51 2016 -0800
@@ -1346,9 +1346,9 @@
         }

         static final class OfRef<T> extends InfiniteSupplyingSpliterator<T> {
-            final Supplier<T> s;
+            final Supplier<? extends T> s;

-            OfRef(long size, Supplier<T> s) {
+            OfRef(long size, Supplier<? extends T> s) {
                 super(size);
                 this.s = s;
             }