*     argument. These are matched by position - the first {@code %s} gets {@code
   *     errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
   *     square braces. Unmatched placeholders will be left as-is.
   * @param errorMessageArgs the arguments to be substituted into the message template. Arguments

    if (getClass().getName().startsWith("com.google.common.util.concurrent.")) {
      builder.append(getClass().getSimpleName());
    } else {
      builder.append(getClass().getName());
    }
    builder.append('@').append(toHexString(identityHashCode(this))).append("[status=");
    if (isCancelled()) {
      builder.append("CANCELLED");
    } else if (isDone()) {
      addDoneString(builder);
    } else {

    StringBuilder buf = new StringBuilder((len * 3 / 2) + 16);

    int oldpos = 0;
    do {
      buf.append(string, oldpos, pos);
      buf.append(replacement);
      oldpos = pos + 1;
      pos = indexIn(string, oldpos);
    } while (pos != -1);

    buf.append(string, oldpos, len);
    return buf.toString();
  }

  /**

    StringBuilder buf = new StringBuilder((len * 3 / 2) + 16);

    int oldpos = 0;
    do {
      buf.append(string, oldpos, pos);
      buf.append(replacement);
      oldpos = pos + 1;
      pos = indexIn(string, oldpos);
    } while (pos != -1);

    buf.append(string, oldpos, len);
    return buf.toString();
  }

  /**

   *     argument. These are matched by position - the first {@code %s} gets {@code
   *     errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
   *     square braces. Unmatched placeholders will be left as-is.
   * @param errorMessageArgs the arguments to be substituted into the message template. Arguments

      return first;
    }

    StringBuilder sb = new StringBuilder().append("expected one element but was: <").append(first);
    for (int i = 0; i < 4 && iterator.hasNext(); i++) {
      sb.append(", ").append(iterator.next());
    }
    if (iterator.hasNext()) {
      sb.append(", ...");
    }
    sb.append('>');

    throw new IllegalArgumentException(sb.toString());
  }

  /**

      return first;
    }

    StringBuilder sb = new StringBuilder().append("expected one element but was: <").append(first);
    for (int i = 0; i < 4 && iterator.hasNext(); i++) {
      sb.append(", ").append(iterator.next());
    }
    if (iterator.hasNext()) {
      sb.append(", ...");
    }
    sb.append('>');

    throw new IllegalArgumentException(sb.toString());
  }

  /**