Add "since" annotations to javadocs for new Experimental/Beta methods

Author: DavidMGross

src/main/java/rx/Observable.java

@@ -1749,6 +1749,7 @@ public final static <T> Observable<T> merge(Observable<? extends Observable<? ex
      * @throws IllegalArgumentException
      *             if {@code maxConcurrent} is less than or equal to 0
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
+     * @since (if this graduates from Experimental/Beta to supported, replace this parenthetical with the release number)
      */
     @Experimental
     @SuppressWarnings({"unchecked", "rawtypes"})
@@ -2047,11 +2048,13 @@ public final static <T> Observable<T> merge(Observable<? extends T>[] sequences)
      *            the maximum number of Observables that may be subscribed to concurrently
      * @return an Observable that emits all of the items emitted by the Observables in the Array
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
+     * @since (if this graduates from Experimental/Beta to supported, replace this parenthetical with the release number)
      */
     @Experimental
     public final static <T> Observable<T> merge(Observable<? extends T>[] sequences, int maxConcurrent) {
         return merge(from(sequences), maxConcurrent);
     }
+
     /**
      * Flattens an Observable that emits Observables into one Observable, in a way that allows an Observer to
      * receive all successfully emitted items from all of the source Observables without being interrupted by
@@ -2079,6 +2082,7 @@ public final static <T> Observable<T> merge(Observable<? extends T>[] sequences,
     public final static <T> Observable<T> mergeDelayError(Observable<? extends Observable<? extends T>> source) {
         return source.lift(OperatorMerge.<T>instance(true));
     }
+
     /**
      * Flattens an Observable that emits Observables into one Observable, in a way that allows an Observer to
      * receive all successfully emitted items from all of the source Observables without being interrupted by
@@ -2105,6 +2109,7 @@ public final static <T> Observable<T> mergeDelayError(Observable<? extends Obser
      * @return an Observable that emits all of the items emitted by the Observables emitted by the
      *         {@code source} Observable
      * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
+     * @since (if this graduates from Experimental/Beta to supported, replace this parenthetical with the release number)
      */
     @Experimental
     public final static <T> Observable<T> mergeDelayError(Observable<? extends Observable<? extends T>> source, int maxConcurrent) {
@@ -5513,6 +5518,7 @@ public final Observable<T> onBackpressureDrop() {
     public final Observable<T> onBackpressureBlock(int maxQueueLength) {
         return lift(new OperatorOnBackpressureBlock<T>(maxQueueLength));
     }
+
     /**
      * Instructs an Observable that is emitting items faster than its observer can consume them to block the
      * producer thread if the number of undelivered onNext events reaches the system-wide ring buffer size.

src/main/java/rx/observers/Subscribers.java

@@ -213,7 +213,7 @@ public final void onNext(T args) {
      *         <code>subscriber</code>, has backpressure controlled by
      *         <code>subscriber</code> and uses <code>subscriber</code> to
      *         manage unsubscription.
-     * 
+     * @since (if this graduates from Experimental/Beta to supported, replace this parenthetical with the release number)
      */
     @Experimental
     public static <T> Subscriber<T> wrap(final Subscriber<? super T> subscriber) {