@VisibleForTesting
    boolean isReceiverLoaded(String serviceName) {
        return delegationTokenReceivers.containsKey(serviceName);
    }
@Test
    public void testAllReceiversLoaded() {
        Configuration configuration = new Configuration();
        configuration.setBoolean(CONFIG_PREFIX + ".throw.enabled", false);
        DelegationTokenReceiverRepository delegationTokenReceiverRepository =
                new DelegationTokenReceiverRepository(configuration, null);

        assertEquals(3, delegationTokenReceiverRepository.delegationTokenReceivers.size());
        assertTrue(delegationTokenReceiverRepository.isReceiverLoaded("hadoopfs"));
        assertTrue(delegationTokenReceiverRepository.isReceiverLoaded("hbase"));
        assertTrue(delegationTokenReceiverRepository.isReceiverLoaded("test"));
        assertTrue(ExceptionThrowingDelegationTokenReceiver.constructed.get());
        assertFalse(delegationTokenReceiverRepository.isReceiverLoaded("throw"));
    }