code: public JenkinsServer renameJob(FolderJob folder, String oldJobName, String newJobName, Boolean crumbFlag)
              throws IOException {
          client.post(UrlUtils.toJobBaseUrl(folder, oldJobName) 
              + "/doRename?newName=" + EncodingUtils.formParameter(newJobName),
                 crumbFlag);
          return this;
      }
docs: Rename a job
  
  @param folder {@link FolderJob}
  @param oldJobName existing job name.
  @param newJobName The new job name.
  @param crumbFlag <code>true</code> to add <b>crumbIssuer</b>
  <code>false</code> otherwise.
  @throws IOException In case of a failure.