Making sameThreadScheduledExecutor's return type ListeningScheduledExecutorService, to avoid leaking a package-private class through a public method.

RELNOTES=`testing`: Changed the return type of `sameThreadScheduledExecutor` to `ListeningScheduledExecutorService` to avoid leaking a package-private class through a public method. This helps Kotlin callers.
PiperOrigin-RevId: 488662036

Author: java-team-github-bot

android/guava-testlib/src/com/google/common/util/concurrent/testing/TestingExecutors.java

@@ -88,9 +88,9 @@ public static ListeningScheduledExecutorService noOpScheduledExecutor() {
    * invokeAll/invokeAny} throwing RejectedExecutionException, although a subset of the tasks may
    * already have been executed.
    *
-   * @since 15.0
+   * @since NEXT (taking the place of a method with a different return type from 15.0)
    */
-  public static SameThreadScheduledExecutorService sameThreadScheduledExecutor() {
+  public static ListeningScheduledExecutorService sameThreadScheduledExecutor() {
     return new SameThreadScheduledExecutorService();
   }
 

guava-testlib/src/com/google/common/util/concurrent/testing/TestingExecutors.java

@@ -88,9 +88,9 @@ public static ListeningScheduledExecutorService noOpScheduledExecutor() {
    * invokeAll/invokeAny} throwing RejectedExecutionException, although a subset of the tasks may
    * already have been executed.
    *
-   * @since 15.0
+   * @since NEXT (taking the place of a method with a different return type from 15.0)
    */
-  public static SameThreadScheduledExecutorService sameThreadScheduledExecutor() {
+  public static ListeningScheduledExecutorService sameThreadScheduledExecutor() {
     return new SameThreadScheduledExecutorService();
   }