assertNull(array[0]);
  }

  @GwtIncompatible // ObjectArrays.concat(Object[], Object[], Class)
  public void testConcatEmptyEmpty() {
    String[] result = ObjectArrays.concat(new String[0], new String[0], String.class);
    assertEquals(String[].class, result.getClass());
    assertThat(result).isEmpty();
  }

  @GwtIncompatible // ObjectArrays.concat(Object[], Object[], Class)
  public void testConcatEmptyNonempty() {

   * write.
   *
   * 2. visibility of the writes to an afterDone() call triggered by cancel():
   *
   * Since these fields are non-final that means that TimeoutFuture is not being 'safely published',
   * thus a motivated caller may be able to expose the reference to another thread that would then
   * call cancel() and be unable to cancel the delegate.

        ImmutableList.copyOf(
            Iterables.concat(
                Iterables.transform(POSITIVE_INTEGER_CANDIDATES, NEGATE_INT),
                ImmutableList.of(Integer.MIN_VALUE)));
    NONZERO_INTEGER_CANDIDATES =
        ImmutableList.copyOf(
            Iterables.concat(POSITIVE_INTEGER_CANDIDATES, NEGATIVE_INTEGER_CANDIDATES));
    ALL_INTEGER_CANDIDATES = Iterables.concat(NONZERO_INTEGER_CANDIDATES, ImmutableList.of(0));
  }

    Stream<String> concatenated =
        Streams.concat(Stream.of("a"), streamB, Stream.empty(), Stream.of("c", "d"));
    assertThat(concatenated).containsExactly("a", "b", "c", "d").inOrder();
    concatenated.close();
    assertThat(closeCountB.get()).isEqualTo(1);
  }

  public void testConcat_refStream_closeIsPropagated_Stream_concat() {
    // Just to demonstrate behavior of Stream::concat in the standard library

    public final void addListener(Runnable listener, Executor executor) {
      super.addListener(listener, executor);
    }

    @CanIgnoreReturnValue
    @Override
    public final boolean cancel(boolean mayInterruptIfRunning) {
      return super.cancel(mayInterruptIfRunning);
    }
  }

  private static final Logger log = Logger.getLogger(AbstractFuture.class.getName());

  private State state;
  private V value;

  }

  private static void doTestSuccessfulAsList_resultCancelledRacingInputDone() throws Exception {
    // Simple (combined.cancel -> input.cancel -> setOneValue):
    successfulAsList(ImmutableList.of(SettableFuture.create())).cancel(true);

    /*
     * Complex (combined.cancel -> input.cancel -> other.set -> setOneValue),
     * to show that this isn't just about problems with the input future we just
     * cancelled:

      Character[] prefix = {Character.MIN_VALUE, Character.MAX_VALUE};
      Character[] suffix = {(char) 86, (char) 99};
      Character[] all = concat(concat(prefix, elements), suffix);
      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Character[] concat(Character[] left, Character[] right) {
    Character[] result = new Character[left.length + right.length];

      Double[] prefix = {Double.MIN_VALUE, Double.MAX_VALUE};
      Double[] suffix = {(double) 86, (double) 99};
      Double[] all = concat(concat(prefix, elements), suffix);
      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Double[] concat(Double[] left, Double[] right) {
    Double[] result = new Double[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);

      Character[] prefix = {Character.MIN_VALUE, Character.MAX_VALUE};
      Character[] suffix = {(char) 86, (char) 99};
      Character[] all = concat(concat(prefix, elements), suffix);
      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Character[] concat(Character[] left, Character[] right) {
    Character[] result = new Character[left.length + right.length];

    String expected = "abcde";

    assertEquals(expected, CharSource.concat(ImmutableList.of(c1, c2, c3)).read());
    assertEquals(expected, CharSource.concat(c1, c2, c3).read());
    assertEquals(expected, CharSource.concat(ImmutableList.of(c1, c2, c3).iterator()).read());
    assertFalse(CharSource.concat(c1, c2, c3).isEmpty());

    CharSource emptyConcat = CharSource.concat(CharSource.empty(), CharSource.empty());