import java.util.List;
import java.util.UUID;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * Represents a chat session containing conversation history.
 *
 * @author FessProject
 */
public class ChatSession {

    /** The unique session identifier. */
    private String sessionId;

    /** The user ID associated with this session. */
    private String userId;

    /** The timestamp when the session was created. */

        session.setMessages(null);
        assertEquals(0, session.getMessageCount());
    }

    @Test
    public void test_clearMessages() {
        final ChatSession session = new ChatSession();
        session.addUserMessage("Message 1");
        session.addAssistantMessage("Message 2");
        assertEquals(2, session.getMessageCount());

    /**
     * Creates a new chat session.
     *
     * @param userId the user ID (can be null for anonymous users)
     * @return the created session
     */
    public ChatSession createSession(final String userId) {
        final ChatSession session = new ChatSession(userId);
        sessionCache.put(session.getSessionId(), session);
        if (logger.isDebugEnabled()) {

                    return "full";
                }
                return defaultValue;
            }
        });

        final ChatSession session = new ChatSession();
        session.addUserMessage("Q1");
        session.addAssistantMessage("A1");
        session.addUserMessage("Q2");
        session.addAssistantMessage("A2");