valueIterator.next();
    valueIterator.remove();
    assertFalse(underlying.containsKey("e"));

    Set<Entry<String, String>> entries = map.entrySet();
    Entry<String, String> firstEntry = entries.iterator().next();
    entries.remove(firstEntry);
    assertFalse(underlying.containsKey("f"));

    Iterator<Entry<String, String>> entryIterator = entries.iterator();
    entryIterator.next();
    entryIterator.remove();

  }

  @Override
  Entry<E> getEntry(int index) {
    return Multisets.immutableEntry(elementSet.asList().get(index), getCount(index));
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return isEmpty() ? null : getEntry(0);
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    return isEmpty() ? null : getEntry(length - 1);
  }

  @Override

      return standardHigherEntry(key);
    }

    @Override
    public @Nullable K higherKey(K key) {
      return standardHigherKey(key);
    }

    @Override
    public @Nullable Entry<K, V> firstEntry() {
      return standardFirstEntry();
    }

    /*
     * We can't override lastEntry to delegate to standardLastEntry, as it would create an infinite

    public @Nullable K higherKey(@ParametricNullness K key) {
      return sortedMap().higherKey(key);
    }

    @Override
    public @Nullable Entry<K, Collection<V>> firstEntry() {
      Entry<K, Collection<V>> entry = sortedMap().firstEntry();
      return (entry == null) ? null : wrapEntry(entry);
    }

    @Override
    public @Nullable Entry<K, Collection<V>> lastEntry() {

     * @param map the sequenced map
     * @return the first entry, or null if the map is empty
     * @since Java 21
     */
    public static <K, V> Map.Entry<K, V> firstEntry(final SequencedMap<K, V> map) {
        return map.isEmpty() ? null : map.firstEntry();
    }

    /**
     * Returns the last entry of a sequenced map.
     *
     * @param <K> the key type
     * @param <V> the value type

        long firstRetry = state.getNextRetryTime();
        state.incrementRetry();

        long secondRetry = state.getNextRetryTime();
        state.incrementRetry();

        long thirdRetry = state.getNextRetryTime();

        // Should have exponential backoff
        assertTrue(secondRetry > firstRetry);
        assertTrue(thirdRetry > secondRetry);
    }