}

  /**
   * Returns the string if it is not null, or an empty string otherwise.
   *
   * @param string the string to test and possibly return
   * @return {@code string} if it is not null; {@code ""} otherwise
   */
  static String nullToEmpty(@CheckForNull String string) {
    return (string == null) ? "" : string;
  }

  /**
   * Returns the string if it is not empty, or a null string otherwise.
   *

final class Platform {

  private static final char[] CHAR_BUFFER = new char[1024];

  static char[] charBufferFromThreadLocal() {
    // ThreadLocal is not available to GWT, so we always reuse the same
    // instance.  It is always safe to return the same instance because
    // javascript is single-threaded, and only used by blocks that doesn't
    // involve async callbacks.
    return CHAR_BUFFER;
  }

  private Platform() {}

  // Use fewer steps in the ListIteratorTester in ListListIteratorTester because it's slow in prod
  // mode.
  static int listListIteratorTesterNumIterations() {
    // TODO(hhchan): It's 4 in java.  Figure out why even 3 is too slow in prod mode.
    return 2;
  }

  // Use fewer steps in the IteratorTester in CollectionIteratorTester because it's slow in prod
  // mode.
  static int collectionIteratorTesterNumIterations() {

  }

  /**
   * Returns the string if it is not null, or an empty string otherwise.
   *
   * @param string the string to test and possibly return
   * @return {@code string} if it is not null; {@code ""} otherwise
   */
  static String nullToEmpty(@CheckForNull String string) {
    return (string == null) ? "" : string;
  }

  /**
   * Returns the string if it is not empty, or a null string otherwise.
   *

  /*
   * If I understand correctly:
   *
   * This needs to be a @JsMethod so that J2CL knows to look for a JavaScript implemention of
   * it in Platform.native.js. (The JavaScript implementation inline below is visible to *GWT*, but
   * *J2CL* doesn't look at it.)
   *
   * However, once it's a @JsMethod, GWT produces a warning. That's because (a) the *other* purpose

    // CharMatcher.precomputed() produces CharMatchers that are maybe a little
    // faster (and that's debatable), but definitely more memory-hungry. We're
    // choosing to turn .precomputed() into a no-op in GWT, because it doesn't
    // seem to be a worthwhile tradeoff in a browser.
    return matcher;
  }

  static String formatCompact4Digits(double value) {
    return "" + ((Number) (Object) value).toPrecision(4);
  }

    return requireNonNull(DEST_TL.get());
  }

  /**
   * A thread-local destination buffer to keep us from creating new buffers. The starting size is
   * 1024 characters. If we grow past this we don't put it back in the threadlocal, we just keep
   * going and grow as needed.
   */
  private static final ThreadLocal<char[]> DEST_TL =
      new ThreadLocal<char[]>() {
        @Override
        protected char[] initialValue() {