for (int i = 0; i < length; i++) {
      checkElementNotNull(array[i], i);
    }
    return array;
  }

  // We do this instead of Preconditions.checkNotNull to save boxing and array
  // creation cost.
  @CanIgnoreReturnValue
  static Object checkElementNotNull(@CheckForNull Object element, int index) {
    if (element == null) {
      throw new NullPointerException("at index " + index);

   * needed again; and for short-lived ones, it does not matter.
   */

  /**
   * Padded variant of AtomicLong supporting only raw accesses plus CAS. The value field is placed
   * between pads, hoping that the JVM doesn't reorder them.
   *
   * <p>JVM intrinsics note: It would be possible to use a release-only form of CAS here, if it were
   * provided.
   */
  static final class Cell {

        ensurePositive(xSumOfSquaresOfDeltas * ySumOfSquaresOfDeltas);
    return ensureInUnitRange(sumOfProductsOfDeltas / Math.sqrt(productOfSumsOfSquaresOfDeltas));
  }

  /**
   * Returns a linear transformation giving the best fit to the data according to <a
   * href="http://mathworld.wolfram.com/LeastSquaresFitting.html">Ordinary Least Squares linear

    public boolean contains(@CheckForNull Object target) {
      // Overridden to prevent a ton of boxing
      return (target instanceof Double)
          && Doubles.indexOf(array, (Double) target, start, end) != -1;
    }

    @Override
    public int indexOf(@CheckForNull Object target) {
      // Overridden to prevent a ton of boxing
      if (target instanceof Double) {

        assertFalse(greater.equals(t));
      }
    }
  }

  /**
   * Returns a collection that simulates concurrent modification by having its size method return
   * incorrect values. This is useful for testing methods that must treat the return value from
   * size() as a hint only.
   *

  /**
   * Compares the two specified {@code byte} values, treating them as unsigned values between 0 and
   * 255 inclusive. For example, {@code (byte) -127} is considered greater than {@code (byte) 127}
   * because it is seen as having the value of positive {@code 129}.
   *
   * @param a the first {@code byte} to compare
   * @param b the second {@code byte} to compare

    public boolean contains(@CheckForNull Object target) {
      // Overridden to prevent a ton of boxing
      return (target instanceof Character)
          && Chars.indexOf(array, (Character) target, start, end) != -1;
    }

    @Override
    public int indexOf(@CheckForNull Object target) {
      // Overridden to prevent a ton of boxing
      if (target instanceof Character) {

 * socket option on an IPv6 socket). Yes, it's confusing. Nevertheless, these "mapped" addresses
 * were never supposed to be seen on the wire. That assumption was dropped, some say mistakenly, in
 * later RFCs with the apparent aim of making IPv4-to-IPv6 transition simpler.
 *
 * <p>Technically one <i>can</i> create a 128bit IPv6 address with the wire format of a "mapped"
 * address, as shown above, and transmit it in an IPv6 packet header. However, Java's InetAddress

    }
  }

  /**
   * Creates a new file system for testing that supports the given features in addition to
   * supporting symbolic links. The file system is created initially having the following file
   * structure:
   *
   * <pre>
   *   /
   *      work/
   *         dir/
   *            a
   *            b/
   *               g
   *               h -> ../a

   * <p>Note that, in cases where {@code lengthIfKnown} returns zero, it is <i>possible</i> that
   * chars are actually available for reading. This means that a source may return {@code true} from
   * {@code isEmpty()} despite having readable content.
   *
   * @throws IOException if an I/O error occurs
   * @since 15.0
   */
  public boolean isEmpty() throws IOException {
    Optional<Long> lengthIfKnown = lengthIfKnown();