return new Unhashables();
  }

  @Override
  public T create(Object... elements) {
    UnhashableObject[] array = createArray(elements.length);
    int i = 0;
    for (Object e : elements) {
      array[i++] = (UnhashableObject) e;
    }
    return create(array);
  }

  /**
   * Creates a new collection containing the given elements; implement this method instead of {@link
   * #create(Object...)}.

  @CollectionFeature.Require(absent = REJECTS_DUPLICATES_AT_CREATION)
  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testLastIndexOf_duplicate() {
    E[] array = createSamplesArray();
    array[getNumElements() / 2] = e0();
    collection = getSubjectGenerator().create(array);
    assertEquals(
        "lastIndexOf(duplicate) should return index of last occurrence",
        getNumElements() / 2,
        getList().lastIndexOf(e0()));
  }

    @SuppressWarnings("unchecked")
    Entry<String, String>[] array = (Entry<String, String>[]) new Entry<?, ?>[entries.length];
    int i = 0;
    for (Object o : entries) {
      @SuppressWarnings("unchecked")
      Entry<String, String> e = (Entry<String, String>) o;
      array[i++] = e;
    }
    return create(array);
  }

      return new SampleChars();
    }

    @Override
    public List<Character> create(Object... elements) {
      Character[] array = new Character[elements.length];
      int i = 0;
      for (Object e : elements) {
        array[i++] = (Character) e;
      }
      return create(array);
    }

    /**
     * Creates a new collection containing the given elements; implement this method instead of

      return new SampleDoubles();
    }

    @Override
    public List<Double> create(Object... elements) {
      Double[] array = new Double[elements.length];
      int i = 0;
      for (Object e : elements) {
        array[i++] = (Double) e;
      }
      return create(array);
    }

    /**
     * Creates a new collection containing the given elements; implement this method instead of

      return new SampleChars();
    }

    @Override
    public List<Character> create(Object... elements) {
      Character[] array = new Character[elements.length];
      int i = 0;
      for (Object e : elements) {
        array[i++] = (Character) e;
      }
      return create(array);
    }

    /**
     * Creates a new collection containing the given elements; implement this method instead of

   * should process the bytes from {@code buf[off]} through {@code buf[off + len - 1]} (inclusive).
   *
   * @param buf the byte array containing the data to process
   * @param off the initial offset into the array
   * @param len the length of data to be processed
   * @return true to continue processing, false to stop
   */

  }

  @Override
  public @Nullable Object[] toArray() {
    return ObjectArrays.toArrayImpl(this);
  }

  @Override
  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
  public <T extends @Nullable Object> T[] toArray(T[] a) {
    return ObjectArrays.toArrayImpl(this, a);
  }

  @Override

      throw new Error();
    } catch (AssertionFailedError expected) {
    }
  }

  public void testAssertEqualInOrder() {
    List<?> list = Arrays.asList("a", "b", "c");
    Helpers.assertEqualInOrder(list, list);

    List<?> fewer = Arrays.asList("a", "b");
    try {
      Helpers.assertEqualInOrder(list, fewer);
      throw new Error();
    } catch (AssertionFailedError expected) {
    }

    try {

            .addValue("z")
            .addValue("")
            .addValue(null)
            .add(SHORT_NAME, Arrays.asList("A"))
            .add(LONG_NAME, Arrays.asList("B"))
            .add(SHORT_NAME, Arrays.asList())
            .add(LONG_NAME, Arrays.asList())
            .addValue(Arrays.asList("C"))
            .addValue(Arrays.asList())
            .add(SHORT_NAME, Collections.singletonMap("k1", "v1"))