Corrected return type in doc for F.reduce(seed, reducer), F.reduceWith(seedSupplier, reducer) and O.reduce(seed, reducer) (#5478)

Author: ganapathi004

src/main/java/io/reactivex/Flowable.java

@@ -10787,7 +10787,7 @@ public final Maybe<T> reduce(BiFunction<T, T, T> reducer) {
      * @param reducer
      *            an accumulator function to be invoked on each item emitted by the source Publisher, the
      *            result of which will be used in the next accumulator call
-     * @return a Flowable that emits a single item that is the result of accumulating the output from the
+     * @return a Single that emits a single item that is the result of accumulating the output from the
      *         items emitted by the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      * @see <a href="http://en.wikipedia.org/wiki/Fold_(higher-order_function)">Wikipedia: Fold (higher-order function)</a>
@@ -10803,7 +10803,7 @@ public final <R> Single<R> reduce(R seed, BiFunction<R, ? super T, R> reducer) {
     }
 
     /**
-     * Returns a Flowable that applies a specified accumulator function to the first item emitted by a source
+     * Returns a Single that applies a specified accumulator function to the first item emitted by a source
      * Publisher and a seed value derived from calling a specified seedSupplier, then feeds the result
      * of that function along with the second item emitted by a Publisher into the same function, and so on until
      * all items have been emitted by the source Publisher, emitting the final result from the final call to your
@@ -10828,7 +10828,7 @@ public final <R> Single<R> reduce(R seed, BiFunction<R, ? super T, R> reducer) {
      * @param reducer
      *            an accumulator function to be invoked on each item emitted by the source Publisher, the
      *            result of which will be used in the next accumulator call
-     * @return a Flowable that emits a single item that is the result of accumulating the output from the
+     * @return a Single that emits a single item that is the result of accumulating the output from the
      *         items emitted by the source Publisher
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      * @see <a href="http://en.wikipedia.org/wiki/Fold_(higher-order_function)">Wikipedia: Fold (higher-order function)</a>

src/main/java/io/reactivex/Observable.java

@@ -9027,7 +9027,7 @@ public final Maybe<T> reduce(BiFunction<T, T, T> reducer) {
      * @param reducer
      *            an accumulator function to be invoked on each item emitted by the source ObservableSource, the
      *            result of which will be used in the next accumulator call
-     * @return an Observable that emits a single item that is the result of accumulating the output from the
+     * @return a Single that emits a single item that is the result of accumulating the output from the
      *         items emitted by the source ObservableSource
      * @see <a href="http://reactivex.io/documentation/operators/reduce.html">ReactiveX operators documentation: Reduce</a>
      * @see <a href="http://en.wikipedia.org/wiki/Fold_(higher-order_function)">Wikipedia: Fold (higher-order function)</a>