Retrofit - handle JSON key which has a dynamic structure - Array/Object

I hope this will solve your problem.

First of all, in your case, if you have declared secondaryUser as object or Array, change it to List<SecondaryUser> secondaryUser

Create a deserializer.

DynamicJsonConverter.java

public class DynamicJsonConverter implements Converter {

    private static String fromStream(InputStream in) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        StringBuilder out = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null) {
            out.append(line);

        }
        return out.toString();
    }

    @Override
    public Object fromBody(TypedInput typedInput, Type type) throws ConversionException {
        try {
            InputStream in = typedInput.in(); // convert the typedInput to String
            String string = fromStream(in);
            in.close(); // we are responsible to close the InputStream after use
            return string;

        } catch (Exception e) { // a lot may happen here, whatever happens
            throw new ConversionException(e); // wrap it into ConversionException so retrofit can process it
        }

    }

    @Override
    public TypedOutput toBody(Object object) { // not required
        return null;
    }
}

Your Rest Adapter class.

BasePathAdapterForDynamicJSONKeys.java

 public class BasePathAdapterForDynamicJSONKeys {
        private static RetroFitInterface topRecommendationsInterface;

        public static RetroFitInterface getCommonPathInterface() {

            RestAdapter restAdapter = new RestAdapter.Builder()
                    .setEndpoint(baseURL)
                    .setConverter(new DynamicJsonConverter())

                    .build();
            topRecommendationsInterface = restAdapter.create(RetroFitInterface.class);
            return topRecommendationsInterface;
        }

Also, use the callback as Callback<String>() instead of Callback<YourObject>()

Now, inside the your activity/fragment, inside the success method of retrofit callback, use this.

@Override
 public void success(String myData, Response response) {
 JSONObject mainObject = null;
 mainObject = new JSONObject(myData);

//You can also use JSONObject, depends on what type the response is

 JSONArray myJsonArray = mainObject.getJSONArray("yourkey");

And finally, dump this inside your arraylist.(This is basically conversion of JSON array to arraylist :))

 ArrayList<MyObj> menuDetails = new Gson().fromJson(myJsonArray.toString(), new TypeToken<List<MyObj>>(){}.getType());