private final Adder adder;

    FailsToForwardReturnValue(Adder adder) {
      this.adder = adder;
    }

    @Override
    public int add(int a, int b) {
      return adder.add(a, b) + 1;
    }

    @Override
    public String toString() {
      return adder.toString();
    }
  }

  private static final class FailsToPropagateException implements Adder {

    assertTrue(
        "addAll(allPresent) should return true", getList().addAll(MinimalCollection.of(e0())));
    expectAdded(e0());
  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  public void testAddAll_unsupportedAllPresent() {
    assertThrows(
        UnsupportedOperationException.class, () -> getList().addAll(MinimalCollection.of(e0())));
    expectUnchanged();

                try (InputStream is = urls.nextElement().openStream()) {
                    ExtensionDescriptor descriptor = BUILDER.build(is);
                    artifacts.addAll(descriptor.getExportedArtifacts());
                    packages.addAll(descriptor.getExportedPackages());
                }
            }
        } catch (IOException ignored) {
            // exports descriptors are entirely optional
        }

 * methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change the
 * behavior of {@link #addAll}, which can lead to unexpected behavior. In this case, you should
 * override {@code addAll} as well, either providing your own implementation, or delegating to the
 * provided {@code standardAddAll} method.
 *

              @Override
              public SortedSet<String> create(String[] elements) {
                SortedSet<String> set = new TreeSet<>(arbitraryNullFriendlyComparator());
                Collections.addAll(set, elements);
                return set;
              }
            })
        .named("TreeSet, with comparator")
        .withFeatures(
            SetFeature.GENERAL_PURPOSE,

    assertTrue(
        "add(somePresent) should return true", getSet().addAll(MinimalCollection.of(e3(), e0())));
    expectAdded(e3());
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testAddAll_withDuplicates() {
    MinimalCollection<E> elementsToAdd = MinimalCollection.of(e3(), e4(), e3(), e4());
    assertTrue("add(hasDuplicates) should return true", getSet().addAll(elementsToAdd));
    expectAdded(e3(), e4());
  }

      assertTrue(Thread.holdsLock(mutex));
      return delegate.containsAll(collection);
    }

    @Override
    public boolean addAll(Collection<? extends E> collection) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.addAll(collection);
    }

    @Override
    public boolean retainAll(Collection<?> collection) {
      assertTrue(Thread.holdsLock(mutex));

		server := NewServer(testCase.addrs).
			UseHandler(testCase.handler)
		if testCase.certFn != nil {
			server = server.UseTLSConfig(&tls.Config{
				PreferServerCipherSuites: true,
				GetCertificate:           testCase.certFn,
			})
		}
		if server == nil {
			t.Fatalf("Case %v: server: expected: <non-nil>, got: <nil>", (i + 1))
		} else if !reflect.DeepEqual(server.Addrs, testCase.addrs) {

    private <T> Collection<T> getExtensionComponents(Collection<MavenProject> projects, Class<T> role) {
        Collection<T> foundComponents = new LinkedHashSet<>();
        foundComponents.addAll(lookup.lookupList(role));
        foundComponents.addAll(getProjectScopedExtensionComponents(projects, role));
        return foundComponents;
    }

      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<E> addAll(Iterable<? extends E> elements) {
      super.addAll(elements);
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<E> addAll(Iterator<? extends E> elements) {
      super.addAll(elements);
      return this;
    }

    @CanIgnoreReturnValue