return lastAccessedAt;
    }

    /**
     * Sets the last accessed timestamp.
     *
     * @param lastAccessedAt the last accessed timestamp
     */
    public void setLastAccessedAt(final LocalDateTime lastAccessedAt) {
        this.lastAccessedAt = lastAccessedAt;
    }

    /**
     * Returns a copy of the message list in this session.
     *

        final List<ChatMessage> messages = new ArrayList<>();

        session.setSessionId("session-456");
        session.setUserId("user-789");
        session.setCreatedAt(createdAt);
        session.setLastAccessedAt(lastAccessedAt);
        session.setMessages(messages);

        assertEquals("session-456", session.getSessionId());
        assertEquals("user-789", session.getUserId());