@Test
public void testKeyRefresherException() {

    KeyRefresherException keyRefresherException = new KeyRefresherException();
    assertEquals(null, keyRefresherException.getMessage());
    
    keyRefresherException = new KeyRefresherException("exception");
    assertEquals("exception", keyRefresherException.getMessage());
    
    keyRefresherException = new KeyRefresherException(new Throwable("new throwable"));
    assertEquals("java.lang.Throwable: new throwable", keyRefresherException.getMessage());
    keyRefresherException = new KeyRefresherException("exception", new Throwable("new throwable"));
    assertEquals("exception", keyRefresherException.getMessage());
}