assertEquals(HashMultiset.create(asList("a", "b", "b", "b", "c")), multiset);
  }

  public void testBuilderAddAllIterator() {
    Iterator<String> iterator = asList("a", "b", "a", "c").iterator();
    ImmutableMultiset<String> multiset =
        new ImmutableMultiset.Builder<String>().addAll(iterator).build();
    assertEquals(HashMultiset.create(asList("a", "b", "a", "c")), multiset);
  }

                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
        }

      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));

    public boolean add(@Nullable E o) {
      assertTrue(Thread.holdsLock(mutex));
      return super.add(o);
    }

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

    @Override
    public void clear() {
      assertTrue(Thread.holdsLock(mutex));
      super.clear();
    }

    @Override

  }

  public void testBuilderAddAll_iterable() {
    List<String> a = asList("a", "b");
    List<String> b = asList("c", "d");
    ImmutableList<String> list = new ImmutableList.Builder<String>().addAll(a).addAll(b).build();
    assertEquals(asList("a", "b", "c", "d"), list);
    b.set(0, "f");
    assertEquals(asList("a", "b", "c", "d"), list);
  }

  public void testBuilderAddAll_iterator() {

    emptyAccumulatorByAddAllEmptyPairedStats.addAll(emptyAccumulator.snapshot());

    oneValueAccumulator = new PairedStatsAccumulator();
    oneValueAccumulator.add(ONE_VALUE, OTHER_ONE_VALUE);

    oneValueAccumulatorByAddAllEmptyPairedStats = new PairedStatsAccumulator();
    oneValueAccumulatorByAddAllEmptyPairedStats.add(ONE_VALUE, OTHER_ONE_VALUE);
    oneValueAccumulatorByAddAllEmptyPairedStats.addAll(emptyAccumulator.snapshot());

    emptyAccumulatorByAddAllEmptyPairedStats.addAll(emptyAccumulator.snapshot());

    oneValueAccumulator = new PairedStatsAccumulator();
    oneValueAccumulator.add(ONE_VALUE, OTHER_ONE_VALUE);

    oneValueAccumulatorByAddAllEmptyPairedStats = new PairedStatsAccumulator();
    oneValueAccumulatorByAddAllEmptyPairedStats.add(ONE_VALUE, OTHER_ONE_VALUE);
    oneValueAccumulatorByAddAllEmptyPairedStats.addAll(emptyAccumulator.snapshot());

              @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,

    protected fun collectImports(diagnosticList: HLDiagnosticList): Collection<String> = buildSet {
        addAll(defaultImports)
        for (diagnostic in diagnosticList.diagnostics) {
            diagnostic.original.psiType.collectClassNamesTo(this)
            diagnostic.parameters.forEach { diagnosticParameter ->
                addAll(collectImportsForDiagnosticParameter(diagnosticParameter))
            }
        }
    }

  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testAddAll_emptySet() {
    assertFalse(getMultiset().addAll(Collections.<E>emptySet()));
    expectUnchanged();
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testAddAll_emptyMultiset() {
    assertFalse(getMultiset().addAll(getSubjectGenerator().create()));
    expectUnchanged();
  }

  @CollectionFeature.Require(SUPPORTS_ADD)