*
   * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
   */
  public static <E extends @Nullable Object> SetView<E> difference(Set<E> set1, Set<?> set2) {
    checkNotNull(set1, "set1");
    checkNotNull(set2, "set2");

   *
   * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
   */
  public static <E extends @Nullable Object> SetView<E> difference(Set<E> set1, Set<?> set2) {
    checkNotNull(set1, "set1");

  @SuppressWarnings("GoodTime")
  long getAccessTime();

  /** Sets the entry access time in ns. */
  @SuppressWarnings("GoodTime") // b/122668874
  void setAccessTime(long time);

  /** Returns the next entry in the access queue. */
  ReferenceEntry<K, V> getNextInAccessQueue();

  /** Sets the next entry in the access queue. */
  void setNextInAccessQueue(ReferenceEntry<K, V> next);

    }

    /**
     * Gets the response content.
     *
     * @return the content
     */
    public String getContent() {
        return content;
    }

    /**
     * Sets the response content.
     *
     * @param content the content
     */
    public void setContent(final String content) {
        this.content = content;
    }

    /**
     * Gets the finish reason.
     *

     *
     * @return the highlighting type
     */
    public String getType() {
        return type;
    }

    /**
     * Sets the highlighting type with fluent interface.
     *
     * @param type the highlighting type to set
     * @return this HighlightInfo instance for method chaining
     */
    public HighlightInfo type(final String type) {
        this.type = type;
        return this;

            super();
        }

        /**
         * Sets the ID of the updated item.
         * @param id The ID to set.
         * @return This ApiUpdateResponse instance.
         */
        public ApiUpdateResponse id(final String id) {
            this.id = id;
            return this;
        }

        /**
         * Sets whether the item was created or updated.

  @SuppressWarnings("GoodTime")
  long getAccessTime();

  /** Sets the entry access time in ns. */
  @SuppressWarnings("GoodTime") // b/122668874
  void setAccessTime(long time);

  /** Returns the next entry in the access queue. */
  ReferenceEntry<K, V> getNextInAccessQueue();

  /** Sets the next entry in the access queue. */
  void setNextInAccessQueue(ReferenceEntry<K, V> next);

    }

    /**
     * Sets the message ID.
     *
     * @param id the message ID
     */
    public void setId(final String id) {
        this.id = id;
    }

    /**
     * Gets the message role.
     *
     * @return the message role
     */
    public String getRole() {
        return role;
    }

    /**
     * Sets the message role.
     *

  private Iterable<List<Object>> buildCartesianProduct(Set<?>... sets) {
    List<Set<Optional<?>>> optionalSets = Lists.newArrayListWithExpectedSize(sets.length);
    for (Set<?> set : sets) {
      Set<Optional<?>> optionalSet =
          Sets.newLinkedHashSet(Iterables.transform(set, Optional::fromNullable));
      optionalSets.add(optionalSet);
    }
    Set<List<Optional<?>>> cartesianProduct = Sets.cartesianProduct(optionalSets);

    /**
     * Gets the extra parameters for provider-specific settings.
     *
     * @return the extra parameters map, or {@code null} if not set
     */
    public Map<String, String> getExtraParams() {
        return extraParams;
    }

    /**
     * Sets the extra parameters for provider-specific settings.
     *
     * @param extraParams the extra parameters map
     * @return this request for method chaining