//                                                                           =========
    private static final AccessTokenDbm _instance = new AccessTokenDbm();

    private AccessTokenDbm() {
    }

    public static AccessTokenDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

import org.jspecify.annotations.NullUnmarked;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

/**
 * Abstract base class for testing implementations of {@link Graph} interface. Graph instances
 * created for testing should have Integer node and String edge objects.
 *
 * <p>Test cases that should be handled similarly in any graph implementation are included in this

 * behavior:
 *
 * {@snippet :
 * BaseEncoding.base16().lowerCase().decode("deadbeef");
 * }
 *
 * <p>Warning: BaseEncoding instances are immutable. Invoking a configuration method has no effect
 * on the receiving instance; you must store and use the new encoding instance it returns, instead.
 *
 * {@snippet :
 * // Do NOT do this
 * BaseEncoding hex = BaseEncoding.base16();
 * hex.lowerCase(); // does nothing!

   * for {@code minimumBits}, will return identically-behaving {@link HashFunction} instances.
   *
   * @param minimumBits a positive integer. This can be arbitrarily large. The returned {@link
   *     HashFunction} instance may use memory proportional to this integer.
   * @return a hash function, described above, that produces hash codes of length {@code

        map.put(FieldNames.TIMESTAMP, timestamp.toInstant().toEpochMilli());
        return map;
    }

    /**
     * Parses a source map and returns a SuggestItem instance.
     * @param source The source map.
     * @return A SuggestItem instance.
     */
    public static SuggestItem parseSource(final Map<String, Object> source) {
        final String text = source.get(FieldNames.TEXT).toString();

    private Method valueOfMethod;

    private boolean readable = false;

    private boolean writable = false;

    private ParameterizedClassDesc parameterizedClassDesc;

    /**
     * Creates an instance of {@link PropertyDescImpl}.
     *
     * @param propertyName
     *            The property name. Must not be {@literal null} or an empty string.
     * @param propertyType

  }

  @Override
  Set<K> createKeySet() {
    return new KeySet(map);
  }

  final Set<K> createMaybeNavigableKeySet() {
    if (map instanceof NavigableMap) {
      return new NavigableKeySet((NavigableMap<K, Collection<V>>) map);
    } else if (map instanceof SortedMap) {
      return new SortedKeySet((SortedMap<K, Collection<V>>) map);
    } else {
      return new KeySet(map);
    }
  }

    //                                                                           =========
    private static final ElevateWordDbm _instance = new ElevateWordDbm();

    private ElevateWordDbm() {
    }

    public static ElevateWordDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

    //                                                                           =========
    private static final ClickLogDbm _instance = new ClickLogDbm();

    private ClickLogDbm() {
    }

    public static ClickLogDbm getInstance() {
        return _instance;
    }

    // ===================================================================================

 */
public final class IpAddressUtil {

    /**
     * Private constructor to prevent instantiation of utility class.
     */
    private IpAddressUtil() {
        // Utility class - no instances allowed
    }

    /**
     * Determines if the given address string represents an IPv6 address.
     * This method validates the address using InetAddress to ensure it's a valid IPv6 address.
     *