如何根据条件绑定数据到DTO属性？

public class UserDTO {
    private String name;
    private int age;
    private String email;

    // Getters and Setters
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}

public class UserService {
    public UserDTO getUserDetails(boolean includeEmail) {
        UserDTO userDTO = new UserDTO();
        userDTO.setName("John Doe");
        userDTO.setAge(30);

        if (includeEmail) {
            userDTO.setEmail("john.doe@example.com");
        }

        return userDTO;
    }
}

// Usage
public class Main {
    public static void main(String[] args) {
        UserService userService = new UserService();
        UserDTO userWithEmail = userService.getUserDetails(true);
        UserDTO userWithoutEmail = userService.getUserDetails(false);

        System.out.println("User with email: " + userWithEmail.getName() + ", " + userWithEmail.getEmail());
        System.out.println("User without email: " + userWithoutEmail.getName());
    }
}

public UserDTO getUserDetails(boolean includeEmail) {
    UserDTO userDTO = new UserDTO();
    userDTO.setName("John Doe");
    userDTO.setAge(30);

    if (includeEmail && userDTO != null) {
        userDTO.setEmail("john.doe@example.com");
    }

    return userDTO;
}