code: public boolean isAnswersFilled() throws JSONException {
          if (answers == null) {
              return true;
          }
  
          Iterator<String> it = answers.keys();
          while (it.hasNext()) {
              String key = it.next();
              Object value = answers.get(key);
  
              if ((value instanceof String) && value.equals("")) {
                  return false;
              }
          }
  
          return true;
      }
docs: Verifies whether all expected challenges have been answered, or not.
  
  @return <code>true</code> if all answers have been submitted, otherwise <code>false</code>.
  @throws JSONException