* <p>Elements appear in the resulting set in the same order they were first added to the builder.
   *
   * <p>Building does not change the state of the builder, so it is still possible to add more
   * elements and to build again.
   *
   * @since 2.0
   */
  public static class Builder<E> extends ImmutableCollection.Builder<E> {
    /*
     * `impl` is null only for instances of the subclass, ImmutableSortedSet.Builder. That subclass

     * entries are sorted by value. If a key was added more than once, it appears in iteration order
     * based on the first time it was added, again unless {@link #orderEntriesByValue} was called.
     *
     * <p>In the current implementation, all values associated with a given key are stored in the

        transform(errorInput, newOneTimeErrorThrower(), directExecutor());
    errorInput.set(0);

    runGetIdempotencyTest(errorComposedFuture, MyError.class);

    /*
     * Try again when the input's value is already filled in, since the flow is
     * slightly different in that case.
     */
    exceptionComposedFuture =
        transform(exceptionInput, newOneTimeExceptionThrower(), directExecutor());

              case 1:
                return 1;
              case 2:
                return endOfData();
              default:
                throw new AssertionError("Should not have been invoked again");
            }
          }
        };

    assertTrue(iter.hasNext());
    assertEquals(0, (int) iter.next());

    // verify idempotence of hasNext()
    assertTrue(iter.hasNext());

              case 1:
                return 1;
              case 2:
                return endOfData();
              default:
                throw new AssertionError("Should not have been invoked again");
            }
          }
        };

    assertTrue(iter.hasNext());
    assertEquals(0, (int) iter.next());

    // verify idempotence of hasNext()
    assertTrue(iter.hasNext());

              case 1:
                return 1;
              case 2:
                return endOfData();
              default:
                throw new AssertionError("Should not have been invoked again");
            }
          }
        };

    assertTrue(iter.hasNext());
    assertEquals(0, (int) iter.next());

    // verify idempotence of hasNext()
    assertTrue(iter.hasNext());

      for (Future<?> future : localFutures) {
        future.cancel(wasInterrupted);
      }
    }
    /*
     * We don't call clearSeenExceptions() until processCompleted(). Prior to that, it may be needed
     * again if some outstanding input fails.
     */
  }

  @Override
  @CheckForNull
  protected final String pendingToString() {
    ImmutableCollection<? extends Future<?>> localFutures = futures;

    public <T> T[] toArray(T[] array) {
      return snapshot().toArray(array);
    }

    /*
     * We'd love to use 'new ArrayList(this)' or 'list.addAll(this)', but
     * either of these would recurse back to us again!
     */
    private List<E> snapshot() {
      List<E> list = Lists.newArrayListWithExpectedSize(size());
      for (Multiset.Entry<E> entry : entrySet()) {
        E element = entry.getElement();

    future. (Previously, we sometimes removed such APIs after a deprecation
    period. The last release to remove non-`@Beta` APIs was Guava 21.0.) Even
    `@Deprecated` APIs will remain (again, unless they are `@Beta`). We have no
    plans to start removing things again, but officially, we're leaving our
    options open in case of surprises (like, say, a serious security problem).

3.  Guava has one dependency that is needed for linkage at runtime:

        Dummy sneaky = map.putIfAbsent(sample, Dummy.VALUE);
        if (sneaky == null) {
          return sample;
        } else {
          /* Someone beat us to it! Trying again...
           *
           * Technically this loop not guaranteed to terminate, so theoretically (extremely
           * unlikely) this thread might starve, but even then, there is always going to be another