StringBuilder sb =
          new StringBuilder().append("expected one element but was: <").append(element);
      for (Object o : extras) {
        sb.append(", ").append(o);
      }
      if (overflow) {
        sb.append(", ...");
      }
      sb.append('>');
      throw new IllegalArgumentException(sb.toString());
    }

    void add(Object o) {

    checkNotNull(string); // eager for GWT.
    if (string.length() >= minLength) {
      return string;
    }
    StringBuilder sb = new StringBuilder(minLength);
    for (int i = string.length(); i < minLength; i++) {
      sb.append(padChar);
    }
    sb.append(string);
    return sb.toString();
  }

  /**
   * Returns a string, of length at least {@code minLength}, consisting of {@code string} appended

        if (utf8Length != Utf8.encodedLength(sb)) {
          StringBuilder repro = new StringBuilder();
          for (int j = 0; j < sb.length(); j++) {
            repro.append(" ").append((int) sb.charAt(j)); // GWT compatible
          }
          assertEquals(repro.toString(), utf8Length, Utf8.encodedLength(sb));
        }
      }
    }
  }

  public void testEncodedLength_invalidStrings() {

      StringBuilder sb = new StringBuilder();
      for (int j = 0; j < charCount; j++) {
        int codePoint;
        // discard illegal surrogate "codepoints"
        do {
          codePoint = rnd.nextInt(maxCodePoint.value);
        } while (Character.isSurrogate((char) codePoint));
        sb.appendCodePoint(codePoint);
      }
      strings[i] = sb.toString();
    }
  }

  @Benchmark

    StringBuilder sb = newStringBuilderForCollection(collection.size()).append('[');
    boolean first = true;
    for (Object o : collection) {
      if (!first) {
        sb.append(", ");
      }
      first = false;
      if (o == collection) {
        sb.append("(this Collection)");
      } else {
        sb.append(o);
      }
    }
    return sb.append(']').toString();
  }

      fail();
    } catch (NullPointerException expected) {
    }

    assertEquals("a:00;00:b", j.useForNull("00").join(mapWithNulls));

    StringBuilder sb = new StringBuilder();
    j.appendTo(sb, ImmutableMap.of(1, 2, 3, 4, 5, 6));
    assertEquals("1:2;3:4;5:6", sb.toString());
  }

  public void testEntries() {
    MapJoiner j = Joiner.on(";").withKeyValueSeparator(":");

    StringBuilder sb = new StringBuilder();
    Random random = new Random(0xdeadbeef); // for unpredictable but reproducible behavior
    sb.ensureCapacity(size);
    for (int k = 0; k < size; k++) {
      // [9-127) includes all ascii non-control characters
      sb.append((char) (random.nextInt(127 - 9) + 9));
    }
    String string = sb.toString();
    sb.setLength(0);

    StringBuilder sb = new StringBuilder();
    Random random = new Random(0xdeadbeef); // for unpredictable but reproducible behavior
    sb.ensureCapacity(size);
    for (int k = 0; k < size; k++) {
      // [9-127) includes all ascii non-control characters
      sb.append((char) (random.nextInt(127 - 9) + 9));
    }
    String string = sb.toString();
    sb.setLength(0);

    int spaceInAscii = 32;
    int sevenBitAsciiMax = 128;
    StringBuilder sb = new StringBuilder(sevenBitAsciiMax - spaceInAscii);
    for (int ch = spaceInAscii; ch < sevenBitAsciiMax; ch++) {
      sb.append((char) ch);
    }
    ASCII_CHARACTERS = sb.toString();
  }

  private static final String ALL_DIGITS;

  static {
    StringBuilder sb = new StringBuilder();
    String zeros =

   */
  private static StringBuilder toStringBuilder(Readable r) throws IOException {
    StringBuilder sb = new StringBuilder();
    if (r instanceof Reader) {
      copyReaderToBuilder((Reader) r, sb);
    } else {
      copy(r, sb);
    }
    return sb;
  }

  /**
   * Reads all of the lines from a {@link Readable} object. The lines do not include