@J2ktIncompatible
  @GwtIncompatible // used only in GwtIncompatible tests
  private interface Merger {

    ListenableFuture<List<String>> merged(ListenableFuture<String> a, ListenableFuture<String> b);

    Merger allMerger =
        new Merger() {
          @Override
          public ListenableFuture<List<String>> merged(
              ListenableFuture<String> a, ListenableFuture<String> b) {

  @J2ktIncompatible
  @GwtIncompatible // used only in GwtIncompatible tests
  private interface Merger {

    ListenableFuture<List<String>> merged(ListenableFuture<String> a, ListenableFuture<String> b);

    Merger allMerger =
        new Merger() {
          @Override
          public ListenableFuture<List<String>> merged(
              ListenableFuture<String> a, ListenableFuture<String> b) {

     * ensure that completed write operations performed by other threads are noticed. For most
     * purposes, the "count" field, tracking the number of elements, serves as that volatile
     * variable ensuring visibility. This is convenient because this field needs to be read in many
     * read operations anyway:
     *

   * iterate over keys in their enum definition order, not encounter order.
   *
   * <p>If the mapped keys contain duplicates, the values are merged using the specified merging
   * function.
   *
   * @since 33.2.0 (available since 21.0 in guava-jre)
   */
  @SuppressWarnings({"AndroidJdkLibsChecker", "Java7ApiChecker"})

its hurry to get hold of it; then Alice, thinking it was very
like having a game of play with a cart-horse, and expecting every
moment to be trampled under its feet, ran round the thistle
again; then the puppy began a series of short charges at the
stick, running a very little way forwards each time and a long
way back, and barking hoarsely all the while, till at last it sat
down a good way off, panting, with its tongue hanging out of its