Missing version tag from Single.concatMaps

Author: akarnokd

src/main/java/io/reactivex/rxjava3/core/Single.java

@@ -2699,6 +2699,7 @@ public final <U> Single<U> cast(@NonNull Class<? extends U> clazz) {
      * @return the new {@code Single} returned from {@code mapper} when applied to the item emitted by the current {@code Single}
      * @throws NullPointerException if {@code mapper} is {@code null}
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
+     * @since 3.0.0
      */
     @CheckReturnValue
     @NonNull
@@ -2753,6 +2754,7 @@ public final Completable concatMapCompletable(@NonNull Function<? super T, ? ext
      * @return the new {@code Maybe} returned from {@code mapper} when applied to the item emitted by the current {@code Single}
      * @throws NullPointerException if {@code mapper} is {@code null}
      * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
+     * @since 3.0.0
      */
     @CheckReturnValue
     @NonNull