* @return the user ID
     */
    public String getUserId() {
        return userId;
    }

    /**
     * Sets the user ID.
     *
     * @param userId the user ID
     */
    public void setUserId(final String userId) {
        this.userId = userId;
    }

    /**
     * Gets the creation timestamp.
     *
     * @return the creation timestamp
     */
    public LocalDateTime getCreatedAt() {

        final LocalDateTime lastAccessedAt = LocalDateTime.of(2025, 1, 1, 11, 0);
        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());