* contention. See above for explanation. This method suffers the usual non-modularity problems of
   * optimistic retry code, relying on rechecked sets of reads.
   *
   * @param x the value
   * @param hc the hash code holder
   * @param wasUncontended false if CAS failed before call
   */
  final void retryUpdate(long x, int @Nullable [] hc, boolean wasUncontended) {
    int h;
    if (hc == null) {

    /** Serial version UID for serialization compatibility */
    private static final long serialVersionUID = 1L;

    /**
     * Constructs a new FessUserNotFoundException with the specified username.
     *
     * @param username the username that was not found
     */
    public FessUserNotFoundException(final String username) {
        super("User is not found: " + username);
    }

  ElementOrder<N> incidentEdgeOrder = ElementOrder.unordered();

  @Nullable Integer expectedNodeCount = null;

  /**
   * Creates a new instance with the specified edge directionality.
   *
   * @param directed if true, creates an instance for graphs whose edges are each directed; if
   *     false, creates an instance for graphs whose edges are each undirected.
   */
  AbstractGraphBuilder(boolean directed) {

  }

  /**
   * Returns an immutable multiset entry with the specified element and count. The entry will be
   * serializable if {@code e} is.
   *
   * @param e the element to be associated with the returned entry
   * @param n the count to be associated with the returned entry
   * @throws IllegalArgumentException if {@code n} is negative
   */

  }

  /**
   * Returns an immutable multiset entry with the specified element and count. The entry will be
   * serializable if {@code e} is.
   *
   * @param e the element to be associated with the returned entry
   * @param n the count to be associated with the returned entry
   * @throws IllegalArgumentException if {@code n} is negative
   */

    private static final long serialVersionUID = 1L;

    /**
     * Constructs a new ServletRuntimeException wrapping the given ServletException.
     *
     * @param e The ServletException to wrap
     */
    public ServletRuntimeException(final ServletException e) {
        super(e);
    }

    //                                                                      ==============
    /**
     * Displays the bad request error page.
     *
     * @param form the error form containing error information
     * @return HTML response for the bad request error page
     */
    @Execute
    public HtmlResponse index(final ErrorForm form) {

    /**
     * Default constructor for ErrorBusyAction.
     */
    public ErrorBusyAction() {
        super();
    }

    /**
     * Displays the busy error page.
     *
     * @param form the error form containing error information
     * @return HTML response for the busy error page
     */
    @Execute
    public HtmlResponse index(final ErrorForm form) {

        // Default constructor
    }

    /**
     * Deletes user information records older than the specified number of days.
     * This method is used for data cleanup and maintenance operations.
     *
     * @param days the number of days to keep user information records
     */
    public void deleteBefore(final int days) {
        userInfoBhv.queryDelete(cb -> {

 *
 */
public class JsonUtil {

    /**
     * Defualt constructor.
     */
    protected JsonUtil() {
    }

    /**
     * Escapes a value as Json string.
     *
     * @param value input
     * @return escaped string.
     */
    public static String escape(final String value) {
        if (value == null) {
            return null;
        }

        char c;