code: public Date getBaselineStart()
     {
        Object result = getCachedValue(TaskField.BASELINE_START);
        if (result == null)
        {
           result = getCachedValue(TaskField.BASELINE_ESTIMATED_START);
        }
  
        if (!(result instanceof Date))
        {
           result = null;
        }
        return (Date) result;
     }
docs: The Baseline Start field shows the planned beginning date for a task at
  the time you saved a baseline. Information in this field becomes available
  when you set a baseline.
  
  @return Date