code: public void setJobClass(Class<? extends Job> jobClass) {
  
      if (jobClass == null) {
        throw new IllegalArgumentException("Job class cannot be null.");
      }
  
      if (!Job.class.isAssignableFrom(jobClass)) {
        throw new IllegalArgumentException("Job class must implement the Job interface.");
      }
  
      this.jobClass = jobClass;
    }
docs: Set the instance of <code>Job</code> that will be executed.
  
  @exception IllegalArgumentException if jobClass is null or the class is not a <code>Job</code>.