code: public JenkinsServer updateJob(String jobName, String jobXml, boolean crumbFlag) throws IOException {
          return updateJob(null, jobName, jobXml, crumbFlag);
      }
docs: Update the xml description of an existing job
  
  @param jobName name of the job to be updated.
  @param jobXml the configuration to be used for updating.
  @param crumbFlag true/false.
  @throws IOException in case of an error.