@GwtCompatible
public interface Cache<K, V> {

  /**
   * Returns the value associated with {@code key} in this cache, or {@code null} if there is no
   * cached value for {@code key}.
   *
   * @since 11.0
   */
  @CanIgnoreReturnValue // TODO(b/27479612): consider removing this?
  @Nullable V getIfPresent(@CompatibleWith("K") Object key);

  /**

        return this.credentialType;
    }

    /**
     * Returns the server signature used to validate PAC integrity.
     * @return the server signature
     */
    public PacSignature getServerSignature() {
        return this.serverSignature;
    }

    /**
     * Returns the KDC signature used to validate PAC authenticity.
     * @return the KDC signature
     */
    public PacSignature getKdcSignature() {

    }

    /**
     * Returns the capabilities of the connected share.
     *
     * @return the capabilities
     */
    public int getCapabilities() {
        return this.capabilities;
    }

    /**
     * Returns the maximal access rights that the user has on this share.
     *
     * @return the maximalAccess
     */
    public int getMaximalAccess() {
        return this.maximalAccess;
    }

                && regexMap.equals(rule.regexMap)) {
            return true;
        }
        return false;
    }

    /**
     * Returns the hash code for this RegexRule.
     * @return The hash code.
     */
    @Override
    public int hashCode() {
        int hash = regexMap.hashCode();
        if (defaultRule) {

                return false;
            }
        } else if (!first.equals(other.first)) {
            return false;
        }
        if (second == null) {
            if (other.second != null) {
                return false;
            }
        } else if (!second.equals(other.second)) {
            return false;
        }
        return true;
    }

        @Override
        public CredentialsInternal renew() {
            // Returns itself as the renewed credentials
            return this;
        }
    }

    static class NewRenewingCreds extends BaseCreds {
        @Override
        public CredentialsInternal renew() {
            // Returns a distinct, new credentials instance
            return new NewRenewingCreds();
        }
    }

     *
     * @return the system properties, never {@code null}
     */
    @Nonnull
    Map<String, String> getSystemProperties();

    /**
     * Returns the properly overlaid map of properties: system + user.
     */
    @Nonnull
    Map<String, String> getEffectiveProperties();

    /**
     * Returns the start time of the session.
     *

     */
    public void clear() {
        urlQueueMap.clear();
        sessionMap.clear();
    }

    /**
     * Returns the URL queue for the specified session ID.
     * Creates a new queue if one doesn't exist.
     * @param sessionId the session ID
     * @return the URL queue for the session
     */
    public synchronized Queue<UrlQueueImpl<Long>> getUrlQueueList(final String sessionId) {

    }

    /**
     * Returns the crawler client factory.
     * @return The CrawlerClientFactory instance.
     */
    public CrawlerClientFactory getClientFactory() {
        return clientFactory;
    }

    /**
     * Checks if the crawler is running in background mode.
     * @return true if in background mode, false otherwise.
     */

    implements Serializable {

  /**
   * Returns an empty multimap.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  public static <K, V> ImmutableMultimap<K, V> of() {
    return ImmutableListMultimap.of();
  }

  /** Returns an immutable multimap containing a single entry. */
  public static <K, V> ImmutableMultimap<K, V> of(K k1, V v1) {
    return ImmutableListMultimap.of(k1, v1);
  }