The problem was mixing bytes and str values. Ensuring that everything is in bytes makes it work because urandom returns bytes.

# Encode the concatenated strings into a byte string
chars = (string.ascii_letters + string.digits + string.punctuation).encode()

char_gen = (c for c in map(urandom, repeat(1)) if c in chars)

# Use an empty byte string to join the generated bytes 
pswd_text = b''.join(islice(char_gen, None, string_len))

You can always call pswd_text.decode() to get a unicode string (str).

Try this :

public static class User
{
    public User(int userId, int roleId)
    {
        this.userId = userId;
        this.roleId = roleId;
    }
    private int userId;
    private int roleId;
    public int getUserId()
    {
        return userId;
    }
    public int getRoleId()
    {
        return roleId;
    }
    public void setUserId(int userId)
    {
        this.userId = userId;
    }
    public void setRoleId(int roleId)
    {
        this.roleId = roleId;
    }
}

Test :

Map<String, Object> responseObj = new HashMap<String, Object>();
List<User> userList = new ArrayList<User>();
userList.add(new User(1, 1));
userList.add(new User(2, 2));
responseObj.put("canApprove", true); //1
responseObj.put("approvers", userList);

System.out.println(new JSONObject(responseObj));

Prints :

{"approvers":[{"userId":1,"roleId":1},{"userId":2,"roleId":2}],"canApprove":true}

(formatted)

Here how you can achieve it.

map<string, object> mapToSerialize = new map<string, object>();
mapToSerialize.put('type', 'TEST');
//add you subtype like this
mapToSerialize.put('subtypes', new list<string>{'TEST'});
string jsonstring = JSON.serialize(mapToSerialize);

You can also try something like this with Gson Library:

package com.stackoverflow.works;

import java.lang.reflect.Type;
import java.util.HashMap;
import java.util.Map;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

/*
 * @Author: sarath_sivan
 */

public class MapToJsonConverter {

    /*
     * @Description: Method to convert Map to JSON String
     * @param: map Map<String, String> 
     * @return: json String
     */
    public static String convert(Map<String, String> map) {
        Gson gson = new Gson();
        String json = gson.toJson(map);
        return json;
    }

    /*
     * @Description: Method to convert JSON String to Map
     * @param: json String 
     * @return: map Map<String, String> 
     */
    public static Map<String, String> revert(String json) {
        Gson gson = new Gson();
        Type type = new TypeToken<Map<String, String>>(){}.getType();
        Map<String, String> map = gson.fromJson(json, type);
        return map;
    }

    /*
     * @Description: Method to print elements in the Map
     * @param: map Map<String, String> 
     * @return: void 
     */
    public static void printMap(Map<String, String> map) {
        for (String key : map.keySet()) {
            System.out.println("map.get(\"" + key + "\") = " + map.get(key));
        }
    }

    /*
     * @Description: Method to print the JSON String
     * @param: json String 
     * @return: void 
     */
    public static void printJson(String json) {
        System.out.println("json = " + json);
    }

    /*
     * @Description: Main method to test the JSON-MAP convert/revert logic
     */
    public static void main(String[] args) {
        Map<String, String> paymentCards = new HashMap<String, String>();
        paymentCards.put("card_switch", "Master");
        paymentCards.put("issuing_bank", "ICCI");
        paymentCards.put("card_Type", "DebitCard");

        String json = convert(paymentCards); //converting Map to JSON String
        System.out.println("Map to JSON String");
        System.out.println("******************");
        printJson(json); 

        System.out.println();

        paymentCards = revert(json); //converting JSON String to Map
        System.out.println("JSON String to Map");
        System.out.println("******************");
        printMap(paymentCards);
    }

}

The output look like this:

json.load loads from a file-like object. You either want to use json.loads:

json.loads(data)

Or just use json.load on the request, which is a file-like object:

json.load(request)

Also, if you use the requests library, you can just do:

import requests

json = requests.get(url).json()

You need some key=value pair on each line representing one map entry, and you need quotes around the values:

package main

import (
    "bytes"
    "fmt"
)

func createKeyValuePairs(m map[string]string) string {
    b := new(bytes.Buffer)
    for key, value := range m {
        fmt.Fprintf(b, "%s=\"%s\"\n", key, value)
    }
    return b.String()
}

func main() {
    m := map[string]string{
        "LOG_LEVEL": "DEBUG",
        "API_KEY":   "12345678-1234-1234-1234-1234-123456789abc",
    }
    println(createKeyValuePairs(m))

}

Here is a working example on Go Playground.

json.dumps() converts a dictionary to str object, not a json(dict) object! So you have to load your str into a dict to use it by using json.loads() method

See json.dumps() as a save method and json.loads() as a retrieve method.

This is the code sample which might help you understand it more:

import json

r = {'is_claimed': 'True', 'rating': 3.5}
r = json.dumps(r)
loaded_r = json.loads(r)
loaded_r['rating'] #Output 3.5
type(r) #Output str
type(loaded_r) #Output dict