code: private String resolveEndpointURL() {
          String gerritFrontEndUrl = config.getGerritFrontEndUrl();
          if (!gerritFrontEndUrl.endsWith("/")) {
              gerritFrontEndUrl = gerritFrontEndUrl + "/";
          }
  
          ChangeId changeId = new ChangeId(event.getChange().getProject(), event.getChange().getBranch(),
                  event.getChange().getId());
  
          return gerritFrontEndUrl + "a/changes/" + changeId.asUrlPart()
                  + "/revisions/" + event.getPatchSet().getRevision() + "/review";
      }
docs: What it says resolve Endpoint URL.
  
  @return the url.