code: public Duration getBaselineDuration()
     {
        Object result = getCachedValue(TaskField.BASELINE_DURATION);
        if (result == null)
        {
           result = getCachedValue(TaskField.BASELINE_ESTIMATED_DURATION);
        }
  
        if (!(result instanceof Duration))
        {
           result = null;
        }
        return (Duration) result;
     }
docs: The Baseline Duration field shows the original span of time planned
  to complete a task.
  
  @return  - duration string