Test filtering in ArduinoJson library on ESP32

test1.ino

#include <Arduino.h>
#include <ArduinoJson.h>

void setup() {
  Serial.begin(115200);
  delay(1000);
  int waittime = 3; //wait in seconds 
  Serial.println("Waiting " + String(waittime) + " seconds");  
  for (int i=0; i<waittime; i++)
  {
    delay(1000);
    Serial.println("waiting...");
  }
  
  String fullUserDB = ("{\"USER1\": { \"data\" : { \"1\" : \"item 1 description\", \"2\" : \"item 2 description\"}, \"associated user data\" : \"value\"}, \"USER2\": { \"data\" : { \"10\" : \"item 10 description\", \"11\" : \"item 11 description\"} ,\"associated user data\" : \"value\"}}");
  
  Serial.println("-----------initial json input string: -----------\n" + fullUserDB);

  
  
  DynamicJsonDocument jsonDoc(2000); //jsonDoc to hold the DB
  //deserialize and reserialize to prettify
  DeserializationError err = deserializeJson(jsonDoc, fullUserDB); 
  String prettyUserDB;
  serializeJsonPretty(jsonDoc, prettyUserDB);  
  Serial.println("-----------fullUserDB after prettify (no filter yet): -----------");
  Serial.println(prettyUserDB);
  jsonDoc.clear(); //empty for reuse

  
  //make the filter -- ideally I want to keep the target data of "10" and associated higher levels only --> { USER2, data : {10 : item 10 description}, associated user data: value } <--
  DynamicJsonDocument filter(1000); 
  filter["*"]["data"]["10"] = true;


  Serial.println("make a filter -- \nideally I want to keep the target data of \"10\" and associated higher levels only \n--> { USER2, data : { 10 : item 10 description }, associated user data: value } <--");
  Serial.println("Filter: \nfilter[\"*\"][\"data\"][\"10\"] = true");
  
  //deserialize again -- this time apply filter
  err = deserializeJson(jsonDoc, fullUserDB, DeserializationOption::Filter(filter)); 
  if (err) 
  {
    Serial.println("unable to deserialize DB");
    Serial.println("Error: " + String(err.c_str()));
  }

  
  //reserialize for viewing
  String postFilterJson;
  //serializeJson(jsonDoc, postFilterJson);
  serializeJsonPretty(jsonDoc, postFilterJson);  
  Serial.println("-----------filtered userDB after pretty+filter: -----------");
  Serial.println(postFilterJson);

  Serial.println("Result: Keeping unwanted USER1 and truncated wanted associated user data");

}

void loop() {
  // put your main code here, to run repeatedly:

}