The RestTemplate getForObject() method does not support setting headers. The solution is to use the exchange() method.
So instead of restTemplate.getForObject(url, String.class, param) (which has no headers), use
HttpHeaders headers = new HttpHeaders();
headers.set("Header", "value");
headers.set("Other-Header", "othervalue");
...
HttpEntity entity = new HttpEntity(headers);
ResponseEntity<String> response = restTemplate.exchange(
url, HttpMethod.GET, entity, String.class, param);
Finally, use response.getBody() to get your result.
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