docs: protected static Map<String, String> getHeadersAsMap(ResponseEntity response) {
  
          Map<String, List<String>> headers = new HashMap<>(response.getHeaders());
          Map<String, String> map = new HashMap<>();
  
          for ( Map.Entry<String, List<String>> header :headers.entrySet() ) {
              String headerValue = Joiner.on(",").join(header.getValue());
              map.put(header.getKey(), headerValue);
          }
  
          return map;
      }