@Test(expected = NullPointerException.class)
 public void setTimerTaskNull() throws Exception {
   RecurringTaskHandleImpl handle = new RecurringTaskHandleImpl(scheduler, recurringTestTask);
   handle.setTimerTask(null);
 }
 @Test
 public void scheduleNextRecurrence() throws Exception {
   RecurringTaskHandleImpl handle = new RecurringTaskHandleImpl(scheduler, recurringTestTask);
   handle.scheduleNextRecurrence();
 }