docs: public URI changesUri(Map<String, Object> query) {
          String base_uri = String.format(
                  "%s/%s",
                  this.rootUriString,
                  "_changes"
          );
  
          //lets find the since parameter
          if(query.containsKey("since")){
              Object since = query.get("since");
              if(!(since instanceof String)){
                  //json encode the seq number since it isn't a string
                  query.put("since", JSONUtils.toJson(since));
              }
          }
  
          String uri = appendQueryString(base_uri, query);
          return uriFor(uri);
      }