我创建了一个带有生成器模式的用户类，目的是将其序列化为一个json字符串，以便发布。现在，需求已经改变，我需要能够修补现有记录，更新记录集中的一个或多个字段，但不是所有字段。下面的示例在其用户类中有5个字段，但是想象一下，如果它有30个甚至40个字段，包括int类型。

import com.google.gson.*;

class User 
{
    //All final attributes
    private final String firstName;
    private final String lastName;
    private final int age;
    private final String phone;
    private final String address;

    private User(UserBuilder builder) {
        this.firstName = builder.firstName;
        this.lastName = builder.lastName;
        this.age = builder.age;
        this.phone = builder.phone;
        this.address = builder.address;
    }

    //All getter, and NO setter to provide immutability
    public String getFirstName() {
        return firstName;
    }
    public String getLastName() {
        return lastName;
    }
    public int getAge() {
        return age;
    }
    public String getPhone() {
        return phone;
    }
    public String getAddress() {
        return address;
    }

    public static class UserBuilder 
    {
        private String firstName;
        private String lastName;
        private int age;
        private String phone;
        private String address;

        public UserBuilder() {
        }

        public UserBuilder(String firstName, String lastName) {
            this.firstName = firstName;
            this.lastName = lastName;
        }

        public UserBuilder firstName(String firstName) {
            this.firstName = firstName;
            return this;
        }

        public UserBuilder lastName(String lastName) {
            this.firstName = lastName;
            return this;
        }
        public UserBuilder age(int age) {
            this.age = age;
            return this;
        }
        public UserBuilder phone(String phone) {
            this.phone = phone;
            return this;
        }
        public UserBuilder address(String address) {
            this.address = address;
            return this;
        }
        //Return the finally consrcuted User object
        public User build() {
            User user =  new User(this);
            return user;
        }
    }
}

public class TestUserBuild {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        User user = new User.UserBuilder().
        //No last name
        //No age
        //No phone
        //no address
        .firstName("Super")
        .build();

        System.out.println(user); // User: Super, null, 0, null, null

        Gson gson = new Gson();

        System.out.println(gson.toJson(user)); // {"firstName":"Super","age":0}
    }
}

我没有指定年龄，但它在json字符串中。我认为构建器模式将有助于创建任意数量的json字符串排列，即更新名字和姓氏、仅更新名字、仅更新年龄、仅更新姓氏和电话号码等。。。
对于这个问题，生成器模式方法不是正确的解决方案吗？如果这是一个可接受的解决方案，我如何利用构建器模式将用户类序列化为json字符串，但只使用我选择的字段？在gson库中是否有我可以利用的东西来实现这个任务，比如创建自定义类型适配器？也许我可以创建一个自定义类型适配器，它将所有字段作为输入，检查每个字段是否为null，或者是否为0表示整数，然后只使用delta构建json字符串。