@Override
    MessageBuilder append(char c);

    /**
     * Append content to the message buffer.
     *
     * @param value the content to append
     * @param offset the index of the first {@code char} to append
     * @param len the number of {@code char}s to append
     * @return the current builder
     */
    @Nonnull
    default MessageBuilder a(char[] value, int offset, int len) {

  @Override
  Hasher putBoolean(boolean b);

  @CanIgnoreReturnValue
  @Override
  Hasher putChar(char c);

  /**
   * Equivalent to processing each {@code char} value in the {@code CharSequence}, in order. In
   * other words, no character encoding is performed; the low byte and high byte of each {@code
   * char} are hashed directly (in that order). The input must not be updated while this method is
   * in progress.
   *

            StringUtil.newStringUnsafeMethod = null;
            char[] chars = new char[0];
            assertThat(StringUtil.newStringUnsafe(chars), is(""));
            chars = new char[] { 'a', 'b', 'c' };
            assertThat(StringUtil.newStringUnsafe(chars), is("abc"));
            StringUtil.newStringUnsafeMethod = newStringUnsafeMethod;
            chars = new char[] { 'a', 'b', 'c', ' ' };

            break;
        default:
            break;
        }
        return OptionalEntity.empty();
    }

    /**
     * Create a char mapping item.
     * @param form The create form.
     * @param hook The error hook.
     * @return An optional entity of a char mapping item.
     */
    protected OptionalEntity<CharMappingItem> createCharMappingItem(final CreateForm form, final VaErrorHook hook) {
        try {

    while (lines.peek() == null) {
      Java8Compatibility.clear(cbuf);
      // The default implementation of Reader#read(CharBuffer) allocates a
      // temporary char[], so we call Reader#read(char[], int, int) instead.
      int read = (reader != null) ? reader.read(buf, 0, buf.length) : readable.read(cbuf);
      if (read == -1) {
        lineBuf.finish();
        break;
      }

    assertThat(expected).hasMessageThat().isEqualTo(msg);
  }

  public void testBadArguments_plusforspace() {
    // space can be a safe char if plusForSpace is false
    PercentEscaper unused = new PercentEscaper(" ", false);

    // space cannot be a safe char is plusForSpace is true
    String msg = "plusForSpace cannot be specified when space is a 'safe' character";
    IllegalArgumentException expected =

    assertThat(expected).hasMessageThat().isEqualTo(msg);
  }

  public void testBadArguments_plusforspace() {
    // space can be a safe char if plusForSpace is false
    PercentEscaper unused = new PercentEscaper(" ", false);

    // space cannot be a safe char is plusForSpace is true
    String msg = "plusForSpace cannot be specified when space is a 'safe' character";
    IllegalArgumentException expected =

            + "\u0ce6\u0d66\u0e50\u0ed0\u0f20\u1040\u1090\u17e0\u1810\u1946"
            + "\u19d0\u1b50\u1bb0\u1c40\u1c50\ua620\ua8d0\ua900\uaa50\uff10";
    for (char base : zeros.toCharArray()) {
      for (int offset = 0; offset < 10; offset++) {
        sb.append((char) (base + offset));
      }
    }
    ALL_DIGITS = sb.toString();
  }

  /** Sample CharMatcher instances for benchmarking. */
  public enum SampleMatcherConfig {

   */
  private static char[] growBuffer(char[] dest, int index, int size) {
    if (size < 0) { // overflow - should be OutOfMemoryError but GWT/j2cl don't support it
      throw new AssertionError("Cannot increase internal buffer any further");
    }
    char[] copy = new char[size];
    if (index > 0) {
      System.arraycopy(dest, 0, copy, 0, index);
    }

   */
  private static char[] growBuffer(char[] dest, int index, int size) {
    if (size < 0) { // overflow - should be OutOfMemoryError but GWT/j2cl don't support it
      throw new AssertionError("Cannot increase internal buffer any further");
    }
    char[] copy = new char[size];
    if (index > 0) {
      System.arraycopy(dest, 0, copy, 0, index);
    }