How to convert object to query string with spring (or anything else)?

Question

Is there a way to convert object to query parameters of GET request? Some kind of serializer that converts NameValuePair object to name=aaa&value=bbb, so that string can be attached to the GET request.

In other words, I'm looking for a library that takes
1. url (http://localhost/bla)
2. Object:
public class Obj {
String id;
List<NameValuePair> entities;
}
And converts it to:
http://localhost/bla?id=abc&entities[0].name=aaa&entities[0].value=bbb

Spring RestTemplate is not what I'm looking for as it does all other things except converting object to parameters string.

Answer 1

// object to Map
ObjectMapper objectMapper = new ObjectMapper();
Map<String, String> map = objectMapper.convertValue(obj, new TypeReference<Map<String,String>>() {});

// Map to MultiValueMap
LinkedMultiValueMap<String, String> linkedMultiValueMap = new LinkedMultiValueMap<>();
map.entrySet().forEach(e -> linkedMultiValueMap.add(e.getKey(), e.getValue()));

// call RestTemplate.exchange
return getRestTemplate().exchange(
        uriBuilder().path("your-path").queryParams(linkedMultiValueMap).build().toUri(),
        HttpMethod.GET,
        null,
        new ParameterizedTypeReference<List<YourTypes>>() {}).getBody();