String Array returning [[object Object]] at restTemplate - java

I'm trying to use one api that in the response body we have this structure:
{"flag": false,
"codes":[
"a3f2b9ddf8886b04993632"]}
At Postman, and executing a curl, the response is exactly this one.
But when I use restTemplate.exchange(...) to return the response body,it's always returning for codes: [[object Object]]
UriComponentsBuilder builder = UriComponentsBuilder.fromUri(URL...); //cannot show partner's url here
header.add("Accept", MediaType.APPLICATION_JSON_VALUE);
header.add("Content-Type", MediaType.APPLICATION_JSON_VALUE);
ResponseEntity<String> resourceHttpEntity = restTemplate.exchange(
builder.toUriString(),
HttpMethod.GET,
new HttpEntity<>(header), String.class); //header also has an authorization bearer token that is in another class
System.out.println(resourceHttpEntity.getBody());
Response body from this:
{"flag":false,"codes":["[object Object]"]}
I saw some examples that this occurs, but in Javascript, and we use JSON.stringfy to solve it.
But at Java we don't have this option. I don't know if is a miss-configuration or something.
Even I try to get this response body with the class model using String[], ArrayList for this property. Tried to convert in String.class, JSonNode.class, and it's returning this way.
I tried to use objectMapper to convert, and even test with HTTPURLConnection to confirm and it's happening the same thing. I have the same result.
Any suggestions?

If you need to print the content of a generic object in Json format you can print it as follow:
ObjectWriter ow = new ObjectMapper().writer().withDefaultPrettyPrinter();
System.out.println(ow.writeValueAsString(object));
// Or better log.info(ow.writeValueAsString(object);
If you don't need to format your output you can call directly writeValueAsString on the objectMapper:
Method that can be used to serialize any Java value as a String
System.out.println(new ObjectMapper().writeValueAsString(object));
Updated answer after the update on the question.
It seems that the remote service that you are invoking is returning exactly the body that you showed in the updated answer.
Your code is treating the body as a simple string, so there is no manipulation on the client-side (your code). It means that is possible that for particular values the server-side (the web service that you are invoking) is performing some strange operation (probably a bean to json conversion) that will generate this output.
You have many ways to check it:
make the same call using postman
make the same call using curl
add a sniffer between your client and the server and use it to log the passing data
For the first two alternatives you have to be sure to use exactly the same data used by the java code. And execute them from the same machine (may be that a proxy can change the behaviour of the call).

We discover that the RestTemplate #Bean that we already have in code, was causing this issue. So I just instantiate a new RestTemplate from scratch, and the issue was resolved.
Thank you for your time.

Create Java class with below attributes and use as response entity type.
Public class Response{
boolean flag;
List<String> codes;
}
ResponseEntity<Response> resourceHttpEntity =
restTemplate.exchange(
builder.toUriString(),
HttpMethod.GET,
new HttpEntity<>(header), Response.class);

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Now when i send the request and get a response,every time i need to type cast the response for specific class.i am trying to automate this process,can this be achieved at run time?
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Here every time i need to mention the request and response classes,i don't want to do this.
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Consider using one of the many Java REST libraries. Our client uses the Jersey API to handle requests and responses to our Python based RESTful server.
Jersey uses a class called ClientResponse that stores the generic response data. you can use the getEntity method to return the response as a specific type.
Here is an excerpt of my code, which only deals with strings, but you can see how it could be extended:
ClientResponse response; //a Jersey class
String responseText;
WebResource odbc = resourceCollection.path("ODBC"); //another Jersey class
try {
//we send a POST and get a response stored as generic
response = odbc.type(media)
.accept(MediaType.APPLICATION_XML,MediaType.TEXT_PLAIN)
.post(ClientResponse.class, formdata);
//we pull out the response entity as a string
responseText = response.getEntity(String.class);
} catch (UniformInterfaceException e) {
write("<UniformInterfaceException>\n");
write(" Response type was not expected\n");
write("</UniformInterfaceException>\n");
return;
} catch (ClientHandlerException e) {
write("<Error>\n");
write(" Unable to connect or connection refused\n");
write("</Error>\n");
return;
public class DynamicCasting{
DynamicCasting e1=new DynamicCasting();
private Object obj=new Object();
DynamicCasting.doSomething(obj);
public static DynamicClass doSomething(DynamicClass dynClassObject){
return dynClassObject;
}
}
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#POST
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You can also try SoapUI for REST Tesing

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