while (i + 4 <= utf16Length) {
        char c0 = input.charAt(i);
        char c1 = input.charAt(i + 1);
        char c2 = input.charAt(i + 2);
        char c3 = input.charAt(i + 3);
        if (c0 < 0x80 && c1 < 0x80 && c2 < 0x80 && c3 < 0x80) {
          int k1 = c0 | (c1 << 8) | (c2 << 16) | (c3 << 24);
          k1 = mixK1(k1);
          h1 = mixH1(h1, k1);
          i += 4;

  static long copyReaderToBuilder(Reader from, StringBuilder to) throws IOException {
    checkNotNull(from);
    checkNotNull(to);
    char[] buf = new char[DEFAULT_BUF_SIZE];
    int nRead;
    long total = 0;
    while ((nRead = from.read(buf)) != -1) {
      to.append(buf, 0, nRead);
      total += nRead;
    }
    return total;
  }

  /**

    }

    public void test_execute_withSpecialCharactersInConfig() {
        // Configure field and index names with special characters
        expiresFieldName = "expires-field.with@special#chars";
        documentUpdateIndex = "fess.update-index$special%chars";

        // Re-register FessConfig with updated values
        fessConfig = new TestFessConfig() {
            @Override
            public String getIndexFieldExpires() {

   *
   * @return the replacement characters, or {@code null} if no escaping was required
   */
  @Override
  protected final char @Nullable [] escape(int cp) {
    if (cp < replacementsLength) {
      char[] chars = replacements[cp];
      if (chars != null) {
        return chars;
      }
    }
    if (cp >= safeMin && cp <= safeMax) {
      return null;
    }
    return escapeUnsafe(cp);
  }

          protected void handleLine(String line, String end) {
            lines.add(line + end);
          }
        };
    char[] chars = input.toCharArray();
    int off = 0;
    while (off < chars.length) {
      int len = min(chars.length, off + chunk) - off;
      lineBuf.add(chars, off, len);
      off += len;
    }
    lineBuf.finish();
    return lines;
  }

          protected void handleLine(String line, String end) {
            lines.add(line + end);
          }
        };
    char[] chars = input.toCharArray();
    int off = 0;
    while (off < chars.length) {
      int len = min(chars.length, off + chunk) - off;
      lineBuf.add(chars, off, len);
      off += len;
    }
    lineBuf.finish();
    return lines;
  }

                synonymMap.words.get(bytesReader.readVInt(), scratchBytes);
                if (scratchChars.chars.length < scratchBytes.length) {
                    scratchChars.chars = new char[scratchBytes.length];
                }
                scratchChars.length = UnicodeUtil.UTF8toUTF16(scratchBytes, scratchChars.chars);
                final String word = scratchChars.toString();
                int posInc = 0;

  private static final class AnyOf extends CharMatcher {

    private final char[] chars;

    AnyOf(CharSequence chars) {
      this.chars = chars.toString().toCharArray();
      Arrays.sort(this.chars);
    }

    @Override
    public boolean matches(char c) {
      return Arrays.binarySearch(chars, c) >= 0;
    }

    @Override

      actual += expected;
    }
    assertEquals(EXPECTED_FOUR_BYTE_ROUNDTRIPPABLE_COUNT, actual);
  }

  private static String newString(char... chars) {
    return new String(chars);
  }

  private static byte[] toByteArray(int... bytes) {
    byte[] realBytes = new byte[bytes.length];
    for (int i = 0; i < bytes.length; i++) {
      realBytes[i] = (byte) bytes[i];

        assertNotNull(result);
        // Hexdump uses uppercase letters
        // Note: completionFilter is displayed with 4 hex chars, not 8
        assertTrue(result.contains("fid=0xFFFF"));
        assertTrue(result.contains("filter=0xFFFF")); // Only 4 hex chars are shown
        assertTrue(result.contains("watchTree=true"));
    }

    @Test
    @DisplayName("Test toString method with zero values")