return (ImmutableSet<E>) RegularImmutableSet.EMPTY;
  }

  /**
   * Returns an immutable set containing the given element. Preferred over {@link
   * Collections#singleton} for code consistency, {@code null} rejection, and because the return
   * type conveys the immutability guarantee.
   */
  public static <E> ImmutableSet<E> of(E e1) {
    return new SingletonImmutableSet<>(e1);
  }

  /*

    public String id;

    /**
     * Default constructor for EditForm.
     */
    public EditForm() {
        // Default constructor
    }

    /**
     * Initializes the form by resetting all fields to their default values.
     */
    public void initialize() {
        id = null;
        logType = null;
    }

 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.helper;

import org.lastaflute.web.util.LaRequestUtil;

/**
 * Helper class for detecting and categorizing user agent types from HTTP requests.
 * This class analyzes the User-Agent header to determine which browser type is being used
 * and caches the result in the request attribute for performance optimization.
 *

   * // counters.
   * ListenableFuture<Integer> faultTolerantFuture =
   *     fetchCounters().catching(FetchException.class, x -> 0, directExecutor());
   * }
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See
   * the discussion in the {@link #addListener} documentation. All its warnings about heavyweight

   * // processing the RPC to fetch counters.
   * ListenableFuture<Integer> faultTolerantFuture = Futures.catching(
   *     fetchCounterFuture, FetchException.class, x -> 0, directExecutor());
   * }
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See
   * the warnings the {@link MoreExecutors#directExecutor} documentation.
   *
   * @param input the primary input {@code Future}

     * Initializes the pager with default values for pagination settings.
     */
    public GroupPager() {
        // Default constructor
    }

    /**
     * Clears all pagination data and search criteria, resetting the pager to its initial state.
     * This method resets record counts, pagination flags, and search parameters to their default values.
     */
    public void clear() {
        allRecordCount = 0;

  protected Table<String, Integer, C> table;

  /**
   * Creates a table with the specified data.
   *
   * @param data the table data, repeating the sequence row key, column key, value once per mapping
   * @throws IllegalArgumentException if the size of {@code data} isn't a multiple of 3
   * @throws ClassCastException if a data element has the wrong type
   */

    public String versionNo;

    /** Description of the configuration */
    public String description;

    /**
     * Clears all pagination and configuration data, resetting to default values.
     */
    public void clear() {
        allRecordCount = 0;
        allPageCount = 0;
        existPrePage = false;
        existNextPage = false;
        pageSize = getDefaultPageSize();

 * weak references.
 *
 * <p><strong>Performance</strong>
 *
 * <p>The extra bookkeeping done by cycle detecting locks comes at some cost to performance.
 * Benchmarks (as of December 2011) show that:
 *
 * <ul>
 *   <li>for an unnested {@code lock()} and {@code unlock()}, a cycle detecting lock takes 38ns as
 *       opposed to the 24ns taken by a plain lock.

    }

    /**
     * Gets plugin JAR files from the plugin directory that match the specified filter.
     *
     * @param filter the FilenameFilter to apply when selecting plugin JAR files
     * @return an array of File objects representing matching plugin JAR files, or empty array if none found
     */
    public static File[] getPluginJarFiles(final FilenameFilter filter) {