### Question:
DelegationTokenConfig { public long getTokenLifetime(TimeUnit unit) { requireNonNull(unit); return unit.convert(lifetime, TimeUnit.MILLISECONDS); }  DelegationTokenConfig setTokenLifetime(long lifetime, TimeUnit unit); long getTokenLifetime(TimeUnit unit); @Override boolean equals(Object o); @Override int hashCode(); @Override String toString();  }### Answer:
@Test(expected = NullPointerException.class) public void testGetInvalidTimeUnit() { new DelegationTokenConfig().getTokenLifetime(null); }