/** The key of the message: Size of {item} must be between {min} and {max}. */
    public static final String CONSTRAINTS_Size_MESSAGE = "{constraints.Size.message}";

    /** The key of the message: {item} is invalid credit card number. */
    public static final String CONSTRAINTS_CreditCardNumber_MESSAGE = "{constraints.CreditCardNumber.message}";

    /** The key of the message: {item} is invalid {type} barcode. */

     * the combiner is almost certain to hold its own reference to the futures, and a real app would
     * hold a reference to the executor and thus to the combiner. What we really care about is that
     * the futures are released once the combiner is done running. But we happen to provide this
     * earlier cleanup at the moment, so we're testing it.
     */
    GcFinalization.awaitClear(future1Ref);

    return s.charAt(rand.nextInt(s.length()));
  }

  /**
   * Provides samples on a random distribution derived from the web.
   *
   * <p>Adapted from data provided by Mark Davis.
   *
   * @author Christopher Swenson
   */
  static class CharSamples {

    static {
      populateProb1();
      populateProb2();
      populateChars1();
      populateChars2();

     * the combiner is almost certain to hold its own reference to the futures, and a real app would
     * hold a reference to the executor and thus to the combiner. What we really care about is that
     * the futures are released once the combiner is done running. But we happen to provide this
     * earlier cleanup at the moment, so we're testing it.
     */
    GcFinalization.awaitClear(future1Ref);

    return s.charAt(rand.nextInt(s.length()));
  }

  /**
   * Provides samples on a random distribution derived from the web.
   *
   * <p>Adapted from data provided by Mark Davis.
   *
   * @author Christopher Swenson
   */
  static class CharSamples {

    static {
      populateProb1();
      populateProb2();
      populateChars1();
      populateChars2();