* the same sequence when read using each type of read method it provides.
   */
  private static void assertReadsCorrectly(CharSequence charSequence) throws IOException {
    String expected = charSequence.toString();

    // read char by char
    CharSequenceReader reader = new CharSequenceReader(charSequence);

  @Override
  @CanIgnoreReturnValue
  public Hasher putUnencodedChars(CharSequence charSequence) {
    for (int i = 0, len = charSequence.length(); i < len; i++) {
      putChar(charSequence.charAt(i));
    }
    return this;
  }

  @Override
  @CanIgnoreReturnValue
  public Hasher putString(CharSequence charSequence, Charset charset) {
    return putBytes(charSequence.toString().getBytes(charset));
  }

  @Override

     */
    public StringModelSource(CharSequence pom) {
        this(pom, null);
    }

    /**
     * Creates a new model source backed by the specified string.
     *
     * @param pom The POM's string representation, may be empty or {@code null}.
     * @param location The location to report for this use, may be {@code null}.
     */
    public StringModelSource(CharSequence pom, String location) {

   * the same sequence when read using each type of read method it provides.
   */
  private static void assertReadsCorrectly(CharSequence charSequence) throws IOException {
    String expected = charSequence.toString();

    // read char by char
    CharSequenceReader reader = new CharSequenceReader(charSequence);

     *
     * @param content
     */
    void debug(CharSequence content);

    /**
     * Send a message (and accompanying exception) to the user in the <b>debug</b> error level.<br>
     * The error's stacktrace will be output when this error level is enabled.
     *
     * @param content
     * @param error
     */
    void debug(CharSequence content, Throwable error);

    /**

     */
    public StringSource(CharSequence content) {
        this(content, null);
    }

    /**
     * Creates a new source backed by the specified string.
     *
     * @param content The String representation, may be empty or {@code null}.
     * @param location The location to report for this use, may be {@code null}.
     */
    public StringSource(CharSequence content, String location) {

    }

    @Override
    public void debug(CharSequence content) {
        logger.debug(toString(content));
    }

    private String toString(CharSequence content) {
        if (content == null) {
            return "";
        } else {
            return content.toString();
        }
    }

    @Override
    public void debug(CharSequence content, Throwable error) {

    @DisplayName("Should handle StringBuilder as CharSequence")
    void testJoinWithStringBuilder() {
        StringBuilder sb1 = new StringBuilder("first");
        StringBuilder sb2 = new StringBuilder("second");
        String result = StringUtil.join(",", sb1, sb2);
        assertEquals("first,second", result);
    }

    @Test
    @DisplayName("Should handle StringBuffer as CharSequence")
    void testJoinWithStringBuffer() {

    checkNotClosed();
    target.append(c);
    return this;
  }

  @Override
  public Writer append(@Nullable CharSequence charSeq) throws IOException {
    checkNotClosed();
    target.append(charSeq);
    return this;
  }

  @Override
  public Writer append(@Nullable CharSequence charSeq, int start, int end) throws IOException {
    checkNotClosed();
    target.append(charSeq, start, end);
    return this;

    public DefaultLog(Logger logger) {
        this.logger = requireNonNull(logger);
    }

    @Override
    public void debug(CharSequence content) {
        if (isDebugEnabled()) {
            logger.debug(toString(content));
        }
    }

    @Override
    public void debug(CharSequence content, Throwable error) {
        if (isDebugEnabled()) {
            logger.debug(toString(content), error);
        }
    }