docs: public URI changesUri(String queryKey, Object queryValue) {
  
          if(queryKey.equals("since")){
              if(!(queryValue instanceof String)){
                  //json encode the seq number since it isn't a string
                  Gson gson = new Gson();
                  queryValue = gson.toJson(queryValue);
              }
          }
          return this.path("_changes").query(queryKey, queryValue).build();
      }