assertEquals(1, session.getMessages().size());
        assertEquals("Hello", session.getMessages().get(0).getContent());
        assertTrue(session.getLastAccessedAt().isAfter(beforeAdd) || session.getLastAccessedAt().isEqual(beforeAdd));
    }

    @Test
    public void test_addMessageWithNullMessages() {
        final ChatSession session = new ChatSession();
        session.setMessages(null);

  }

  /**
   * Returns {@code true} if this fluent iterable contains any object for which {@code
   * equals(target)} is true.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.anyMatch(Predicate.isEqual(target))}.
   */
  public final boolean contains(@Nullable Object target) {
    return Iterables.contains(getDelegate(), target);
  }

  /**

  }

  /**
   * Returns {@code true} if this fluent iterable contains any object for which {@code
   * equals(target)} is true.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.anyMatch(Predicate.isEqual(target))}.
   */
  public final boolean contains(@Nullable Object target) {
    return Iterables.contains(getDelegate(), target);
  }

  /**

   *
   * <p><b>Java 8+ users:</b> In most cases, the {@code Stream} equivalent of this method is {@code
   * stream.filter(element::equals).count()}. If {@code element} might be null, use {@code
   * stream.filter(Predicate.isEqual(element)).count()} instead.
   *
   * @see java.util.Collections#frequency(Collection, Object) Collections.frequency(Collection,
   *     Object)
   */