gson

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.annotations.Expose;

public class A {
    @Expose
    private int id = 1;
    @Expose
    private String jsonrpc = "2.0";

    public static String f(Object... a){
        return gson.toJson(a);
    }
    public static    Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();
    public static void main(String[] args) {
        A a = new A();
        System.out.println(f(1, "afdasf", new int[]{1,2}));
    }
}

<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.8.7</version>
</dependency>