I sent a request for question with no parameters to https://api.stackexchange.com/2.2/questions?order=desc&sort=activity&site=stackoverflow

I received a response of 9764 bytes stored in StringBuffer.

The StringBuffer was converted to byte[] to deCompress. GZIPInputStream threw exception :

Not in GZIP format.

Is it necessary to set parameters in request to get response in GZIP format? If not, how to inflate the response?

public class MyConnect {
    private static final String GET_URL = "https://api.stackexchange.com/2.2/questions?order=desc&sort=activity&site=stackoverflow";
    private static void sendGET() throws IOException {
        URL obj = new URL(GET_URL);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();
        con.setRequestMethod("GET");
        int responseCode = con.getResponseCode();
        
        if (responseCode == HttpURLConnection.HTTP_OK){
            BufferedReader in = new BufferedReader(new InputStreamReader(
                con.getInputStream()));
            String inputLine;
            StringBuffer response = new StringBuffer();
            while((inputLine = in.readLine()) != null){
                    response.append(inputLine);
            }
            System.out.println("len: "+ response.length());
            System.out.println("bytes: "+ response.toString().getBytes().length);
            in.close();


            String s = deCompress(response.toString().getBytes());
            if (s != null)
                System.out.println(s);
            else 
                System.out.println("response is null");
            
        }else { 
            //ToD:  error handling.
            System.out.println(responseCode);
        }

    }
    public static void main(String[] args){
        
        try{
            MyConnect.sendGET();
        }catch(IOException e){
            System.out.println("CONNECTION FAILED");
        }finally{
            
        }
    }
    
    private static String deCompress(byte[] str) throws IOException{
        StringBuilder sb = null;
    try{
        ByteArrayInputStream bis = new ByteArrayInputStream(str);
        GZIPInputStream gis = new GZIPInputStream(bis);  // *** exception : not in GZIP format
        BufferedReader br = new BufferedReader(new InputStreamReader(gis, "UTF-8"));
        sb = new StringBuilder();
        String line;
        while ((line = br.readLine()) != null){
            sb.append(line);
        }
        br.close();
        gis.close();
        bis.close();
    }catch(IOException e){
        e.printStackTrace();
    }finally{
        ;
    }
    return sb.toString();

}
    }