// it.
    executeListener(runnable, executor);
  }

  /**
   * Runs this execution list, executing all existing pairs in the order they were added. However,
   * note that listeners added after this point may be executed before those previously added, and
   * note that the execution order of all listeners is ultimately chosen by the implementations of
   * the supplied executors.
   *

 * {@linkplain Comparable natural ordering} also does not permit insertion of non-comparable objects
 * (doing so results in {@code ClassCastException}).
 *
 * <p>This class and its iterator implement all of the optional methods of the {@link
 * Collection} and {@link Iterator} interfaces. The Iterator provided in method {@link #iterator()}

  }

  /**
   * Asserts that all pairs of {@code T} values within {@code valuesInExpectedOrder} are ordered
   * consistently between their order within {@code valuesInExpectedOrder} and the order implied by
   * the given {@code comparator}.
   *
   * <p>In detail, this method asserts
   *
   * <ul>
   *   <li><i>reflexivity</i>: {@code comparator.compare(t, t) = 0} for all {@code t} in {@code

   *       the same.
   *   <li>The special characters ".", "-", "*", and "_" remain the same.
   *   <li>The space character " " is converted into a plus sign "+".
   *   <li>All other characters are converted into one or more bytes using UTF-8 encoding and each
   *       byte is then represented by the 3-character string "%XY", where "XY" is the two-digit,

      new HashMap<>();

  /**
   * Given a set of features, add to it all the features directly or indirectly implied by any of
   * them, and return it.
   *
   * @param features the set of features to expand
   * @return the same set of features, expanded with all implied features
   */
  @CanIgnoreReturnValue
  public static Set<Feature<?>> addImpliedFeatures(Set<Feature<?>> features) {

 * {@link UnsupportedOperationException} when they are not implemented. Most implementations should
 * support either all add operations or none of them, all removal operations or none of them, and if
 * and only if all of these are supported, the {@code setCount} methods as well.
 *
 * <p>A multiset uses {@link Object#equals} to determine whether two instances should be considered

    https://groups.google.com/g/google-web-toolkit-contributors/c/CqYH59Dt_rQ/m/uVGW1QdUsXUJ
    for details.

    The summary is that it ignores one file in favor of the other.
    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
    for prod and one for tests. However, unlike our other packages, as of this
    writing it has test supersource but no prod supersource.

    https://groups.google.com/g/google-web-toolkit-contributors/c/CqYH59Dt_rQ/m/uVGW1QdUsXUJ
    for details.

    The summary is that it ignores one file in favor of the other.
    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
    for prod and one for tests. However, unlike our other packages, as of this
    writing it has test supersource but no prod supersource.

    https://groups.google.com/g/google-web-toolkit-contributors/c/CqYH59Dt_rQ/m/uVGW1QdUsXUJ
    for details.

    The summary is that it ignores one file in favor of the other.
    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
    for prod and one for tests. However, unlike our other packages, as of this
    writing it has test supersource but no prod supersource.

    https://groups.google.com/g/google-web-toolkit-contributors/c/CqYH59Dt_rQ/m/uVGW1QdUsXUJ
    for details.

    The summary is that it ignores one file in favor of the other.
    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
    for prod and one for tests. However, unlike our other packages, as of this
    writing it has test supersource but no prod supersource.