Java to Kotlin Converter

public class User {
    private String id;
    private String name;
    private String email;
    private boolean active;
    
    public User(String id, String name, String email, boolean active) {
        this.id = id;
        this.name = name;
        this.email = email;
        this.active = active;
    }
    
    public String getId() { return id; }
    public void setId(String id) { this.id = id; }
    
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    
    public String getEmail() { return email; }
    public void setEmail(String email) { this.email = email; }
    
    public boolean isActive() { return active; }
    public void setActive(boolean active) { this.active = active; }
    
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof User)) return false;
        User user = (User) o;
        return active == user.active &&
               Objects.equals(id, user.id) &&
               Objects.equals(name, user.name) &&
               Objects.equals(email, user.email);
    }
    
    @Override
    public int hashCode() {
        return Objects.hash(id, name, email, active);
    }
}

data class User(
    val id: String,
    val name: String,
    val email: String,
    val active: Boolean
)

public class UserRepository {
    private List<User> users = new ArrayList<>();
    
    @Nullable
    public User findById(String id) {
        for (User user : users) {
            if (user.getId().equals(id)) {
                return user;
            }
        }
        return null;
    }
    
    public List<String> getActiveUsernames() {
        return users.stream()
            .filter(User::isActive)
            .map(User::getName)
            .collect(Collectors.toList());
    }
    
    public void updateEmail(String userId, String newEmail) {
        User user = findById(userId);
        if (user != null) {
            user.setEmail(newEmail);
        } else {
            throw new IllegalArgumentException("User not found: " + userId);
        }
    }
}

class UserRepository {
    private val users = mutableListOf<User>()
    
    fun findById(id: String): User? {
        return users.find { it.id == id }
    }
    
    fun getActiveUsernames(): List<String> {
        return users.filter { it.active }.map { it.name }
    }
    
    fun updateEmail(userId: String, newEmail: String) {
        val user = findById(userId)
            ?: throw IllegalArgumentException("User not found: $userId")
        user.email = newEmail
    }
}