code: public GitlabServiceJira getJiraService(Integer projectId) throws IOException {
          String tailUrl = GitlabProject.URL + "/" + projectId + GitlabServiceJira.URL;
          return retrieve().to(tailUrl, GitlabServiceJira.class);
      }
docs: Get JIRA service settings for a project.
  https://docs.gitlab.com/ce/api/services.html#get-jira-service-settings
  
  @param projectId The ID of the project containing the variable.
  @return
  @throws IOException on gitlab api call error