* named analogously to their {@code BigInteger} counterparts.
 *
 * <p>The implementations of many methods in this class are based on material from Henry S. Warren,
 * Jr.'s <i>Hacker's Delight</i>, (Addison Wesley, 2002).
 *
 * <p>Similar functionality for {@code long} and for {@link BigInteger} can be found in {@link

public interface Interner<E> {
  /**
   * Chooses and returns the representative instance for any of a collection of instances that are
   * equal to each other. If two {@linkplain Object#equals equal} inputs are given to this method,
   * both calls will return the same instance. That is, {@code intern(a).equals(a)} always holds,
   * and {@code intern(a) == intern(b)} if and only if {@code a.equals(b)}. Note that {@code

     * Gets the system properties to use for interpolation and profile activation. The system properties are collected
     * from the runtime environment like {@link System#getProperties()} and environment variables.
     *
     * @return The system properties, never {@code null}.
     */
    Properties getSystemProperties();

    /**
     * Sets the user properties to use for interpolation and profile activation. The user properties have been

        .test();
  }

  public void testRoundToDouble_maxPreciselyRepresentablePlusOne() {
    double twoToThe53 = Math.pow(2, 53);
    // the representable doubles are 2^53 and 2^53 + 2.
    // 2^53+1 is halfway between, so HALF_UP will go up and HALF_DOWN will go down.
    new RoundToDoubleTester(BigDecimal.valueOf((1L << 53) + 1))
        .setExpectation(twoToThe53, DOWN, FLOOR, HALF_DOWN, HALF_EVEN)

  /**
   * The input futures. After {@link #init}, this field is read only by {@link #afterDone()} (to
   * propagate cancellation) and {@link #toString()}. To access the futures' <i>values</i>, {@code
   * AggregateFuture} attaches listeners that hold references to one or more inputs. And in the case
   * of {@link CombinedFuture}, the user-supplied callback usually has its own references to inputs.
   */
  /*

         * interrupting thread. In theory, interruptTask() should be very fast, but due to
         * InterruptibleChannel and JavaLangAccess.blockedOn(Thread, Interruptible), it isn't
         * predictable what work might be done. (e.g., close a file and flush buffers to disk). To
         * protect ourselves from this, we park ourselves and tell our interrupter that we did so.
         */
        if (state == PARKED || compareAndSet(state, PARKED)) {

   * 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.
   * There are a number of ways to solve this, none of which are very pretty, and it is currently
   * believed to be a purely theoretical problem (since the other actions should supply sufficient
   * write-barriers).
   */

 * #getInstance} are available.
 *
 * <p>Generally, implementations don't support {@link #put} and {@link #putAll} because there is no
 * way to check an object at runtime to be an instance of a {@link TypeToken}. Instead, caller
 * should use the type safe {@link #putInstance}.
 *
 * <p>Also, if caller suppresses unchecked warnings and passes in an {@code Iterable<String>} for

 *       suffice because we our Android users and tests are using the open-source version, which
 *       would no longer have the problematic test. But why bother when we can instead strip it with
 *       a more precisely named annotation?
 *   <li>While a dependency on Android ought to be easy if it's for annotations only, it will
 *       probably require adding the dep to various ACLs, license files, and Proguard

   *       one with {@link CharSequence#charAt(int)}.
   *   <li>use {@link Appendable#append(CharSequence)} in {@link #copyTo(Appendable)} and {@link
   *       #copyTo(CharSink)}. We know this is correct since strings are immutable and so the length
   *       can't change, and it is faster because many writers and appendables are optimized for
   *       appending string instances.
   * </ul>
   */