assertTrue(cycle.hasNext());
    try {
      cycle.remove();
      fail("no exception thrown");
    } catch (IllegalStateException expected) {
    }
  }

  public void testCycleRemoveSameElementTwice() {
    Iterator<String> cycle = Iterators.cycle("a", "b");
    cycle.next();
    cycle.remove();
    try {
      cycle.remove();
      fail("no exception thrown");

                    int size = elements.length;
                    // Remove last element, if size > 1
                    Set<String> set1 =
                        (size > 1)
                            ? Sets.newHashSet(Arrays.asList(elements).subList(0, size - 1))
                            : Sets.newHashSet(elements);
                    // Remove first element, if size > 0
                    Set<String> set2 =

    }

    @Override
    public Iterator<E> iterator() {
      return delegate().iterator(); // manually synchronized
    }

    @Override
    public boolean remove(@CheckForNull Object o) {
      synchronized (mutex) {
        return delegate().remove(o);
      }
    }

    @Override
    public boolean removeAll(Collection<?> c) {
      synchronized (mutex) {
        return delegate().removeAll(c);

   */
  @SuppressWarnings({"AndroidJdkLibsChecker", "Java7ApiChecker"})
  @IgnoreJRERequirement // Users will use this only if they're already using streams.
  @Beta // TODO: b/288085449 - Remove.
  public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
          Comparator<? super K> comparator,
          Function<? super T, ? extends K> keyFunction,

      }

      @Override
      public void remove() {
        iterator.remove();
      }
    };
  }

  /**
   * Returns an iterator that cycles indefinitely over the provided elements.
   *
   * <p>The returned iterator supports {@code remove()}. After {@code remove()} is called,
   * subsequent cycles omit the removed element, but {@code elements} does not change. The

               */
              return uncheckedCastNullableTToT(map.get(key));
            }

            @Override
            public void remove() {
              checkRemove(i == 1);
              i = -1;
              map.remove(key);
            }
          };
        }

        @Override
        public int size() {
          return map.containsKey(key) ? 1 : 0;

    }
  }

  @CheckForNull
  @CanIgnoreReturnValue
  @Override
  public V remove(@CheckForNull Object key) {
    if (key == null) {
      return null;
    }
    int hash = hash(key);
    return segmentFor(hash).remove(key, hash);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
    if (key == null || value == null) {

    assertTrue(cycle.hasNext());
    try {
      cycle.remove();
      fail("no exception thrown");
    } catch (IllegalStateException expected) {
    }
  }

  public void testCycleRemoveSameElementTwice() {
    Iterator<String> cycle = Iterators.cycle("a", "b");
    cycle.next();
    cycle.remove();
    try {
      cycle.remove();
      fail("no exception thrown");

      iterator.next();
      iterator.remove();
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {
    }

    Set<Entry<Integer, String>> entries = unmod.entrySet();
    try {
      Iterator<Entry<Integer, String>> iterator = entries.iterator();
      iterator.next();
      iterator.remove();
      fail("UnsupportedOperationException expected");

      iterator.next();
      iterator.remove();
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {
    }

    Set<Entry<Integer, String>> entries = unmod.entrySet();
    try {
      Iterator<Entry<Integer, String>> iterator = entries.iterator();
      iterator.next();
      iterator.remove();
      fail("UnsupportedOperationException expected");