Set<Object> set = new HashSet<>();
    assertThat(union(emptySet(), emptySet()).copyInto(set)).isSameInstanceAs(set);
    assertThat(intersection(emptySet(), emptySet()).copyInto(set)).isSameInstanceAs(set);
    assertThat(difference(emptySet(), emptySet()).copyInto(set)).isSameInstanceAs(set);
    assertThat(symmetricDifference(emptySet(), emptySet()).copyInto(set)).isSameInstanceAs(set);
  }

  public void testCopyInto_emptySet() {

    assertThat(fluent(1, 3, 5).copyInto(Lists.newArrayList(1, 2)))
        .containsExactly(1, 2, 1, 3, 5)
        .inOrder();
  }

  public void testCopyInto_set() {
    assertThat(fluent(1, 3, 5).copyInto(newHashSet(1, 2))).containsExactly(1, 2, 3, 5);
  }

  public void testCopyInto_setAllDuplicates() {
    assertThat(fluent(1, 3, 5).copyInto(newHashSet(1, 2, 3, 5))).containsExactly(1, 2, 3, 5);
  }

    val keyStore = newEmptyKeyStore(keyStoreType)
    if (heldCertificate != null) {
      val chain = arrayOfNulls<Certificate>(1 + intermediates.size)
      chain[0] = heldCertificate.certificate
      intermediates.copyInto(chain, 1)
      keyStore.setKeyEntry("private", heldCertificate.keyPair.private, password, chain)
    }

    // https://github.com/bcgit/bc-java/issues/1160
    val isBouncyCastle = keyStore.provider.name == "BC"

  //      after: { 11, 11, 22, 22, 33, 33, 00, 00, 00, 00, 00, 00, 77, 77, 88, 88 }
  //
  if (b != address.size) {
    if (compress == -1) return null // Address didn't have compression or enough groups.
    address.copyInto(address, address.size - (b - compress), compress, b)
    address.fill(0.toByte(), compress, compress + (address.size - b))
  }

  return address
}

   * stable. There is usually no reason to retain a reference of type {@code SetView}; typically,
   * you either use it as a plain {@link Set}, or immediately invoke {@link #immutableCopy} or
   * {@link #copyInto} and forget the {@code SetView} itself.
   *
   * @since 2.0
   */
  public abstract static class SetView<E extends @Nullable Object> extends AbstractSet<E> {
    private SetView() {} // no subclasses but our own

   *
   * @param collection the collection to copy elements to
   * @return {@code collection}, for convenience
   * @since 14.0
   */
  @CanIgnoreReturnValue
  public final <C extends Collection<? super E>> C copyInto(C collection) {
    checkNotNull(collection);
    Iterable<E> iterable = getDelegate();
    if (iterable instanceof Collection) {
      collection.addAll((Collection<E>) iterable);
    } else {

HSPLkotlin/collections/ArraysKt___ArraysKt;->asList([Ljava/lang/Object;)Ljava/util/List;
HSPLkotlin/collections/ArraysKt___ArraysKt;->copyInto$default([B[BIIII)[B
HSPLkotlin/collections/ArraysKt___ArraysKt;->copyInto([B[BIII)[B
HSPLkotlin/collections/ArraysKt___ArraysKt;->copyInto([Ljava/lang/Object;[Ljava/lang/Object;III)[Ljava/lang/Object;
HSPLkotlin/collections/ArraysKt___ArraysKt;->fill([Ljava/lang/Object;Ljava/lang/Object;II)V

    assertFalse(writer.closed());
    source.copyTo(writer);
    assertFalse(writer.closed());
  }

  public void testClosesOnErrors_copyingToCharSinkThatThrows() {
    for (TestOption option : EnumSet.of(OPEN_THROWS, WRITE_THROWS, CLOSE_THROWS)) {
      TestCharSource okSource = new TestCharSource(STRING);
      assertThrows(IOException.class, () -> okSource.copyTo(new TestCharSink(option)));

    assertFalse(writer.closed());
    source.copyTo(writer);
    assertFalse(writer.closed());
  }

  public void testClosesOnErrors_copyingToCharSinkThatThrows() {
    for (TestOption option : EnumSet.of(OPEN_THROWS, WRITE_THROWS, CLOSE_THROWS)) {
      TestCharSource okSource = new TestCharSource(STRING);
      assertThrows(IOException.class, () -> okSource.copyTo(new TestCharSink(option)));

}

internal class BufferMockResponseBody(
  val buffer: Buffer,
) : MockResponseBody {
  override val contentLength = buffer.size

  override fun writeTo(sink: BufferedSink) {
    buffer.copyTo(sink.buffer)
    sink.emitCompleteSegments()
  }