@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() {

      checkNotNull(sequence);
      return "";
    }

    @Override
    public String replaceFrom(CharSequence sequence, char replacement) {
      char[] array = new char[sequence.length()];
      Arrays.fill(array, replacement);
      return new String(array);
    }

    @Override
    public String replaceFrom(CharSequence sequence, CharSequence replacement) {

   * {@code b} have no common prefix, returns the empty string.
   *
   * @since 11.0
   */
  public static String commonPrefix(CharSequence a, CharSequence b) {
    checkNotNull(a);
    checkNotNull(b);

    int maxPrefixLength = min(a.length(), b.length());
    int p = 0;
    while (p < maxPrefixLength && a.charAt(p) == b.charAt(p)) {
      p++;

    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;

     * @param elements the elements to join
     * @return elements separated by delimiter
     */
    public static String join(final CharSequence delimiter, final CharSequence... elements) {
        final StringBuilder sb = new StringBuilder();
        for (final CharSequence element : elements) {
            if (sb.length() > 0) {
                if (delimiter != null) {
                    sb.append(delimiter);

        return str == null ? defaultStr : str;
    }

    /**
     * <p>Checks if the CharSequence contains only ASCII printable characters.</p>
     *
     * <p>{@code null} will return {@code false}.
     * An empty CharSequence (length()=0) will return {@code true}.</p>
     *
     * <pre>
     * StringUtils.isAsciiPrintable(null)     = false

     * @return A {@link CopyOptions} with the specified property names to include in the operation.
     * @see CopyOptions#include(CharSequence...)
     */
    public static CopyOptions include(final CharSequence... propertyNames) {
        return new CopyOptions().include(propertyNames);
    }

    /**

import jakarta.validation.ConstraintValidatorContext;

/**
 * Validator implementation for the CustomSize constraint.
 */
public class CustomSizeValidator implements ConstraintValidator<CustomSize, CharSequence> {

    /**
     * Default constructor.
     */
    public CustomSizeValidator() {
        // Empty constructor
    }

    private int min = 0;
    private int max = Integer.MAX_VALUE;

   * @param builder A map builder to which all entries will be added.
   * @return The number of characters consumed from {@code encoded}.
   */
  private static int doParseTrieToBuilder(
      Deque<CharSequence> stack,
      CharSequence encoded,
      int start,
      ImmutableMap.Builder<String, PublicSuffixType> builder) {

    int encodedLen = encoded.length();
    int idx = start;
    char c = '\0';

   * time and space.
   *
   * @throws IllegalArgumentException if {@code sequence} contains ill-formed UTF-16 (unpaired
   *     surrogates)
   */
  public static int encodedLength(CharSequence sequence) {
    // Warning to maintainers: this implementation is highly optimized.
    int utf16Length = sequence.length();
    int utf8Length = utf16Length;
    int i = 0;

    // This loop optimizes for pure ASCII.