@Override
    public TapiNepRef getNepRef(TapiNepRef nepRef) throws NoSuchElementException {
        updateCache();
        TapiNepRef ret = null;
        try {
            ret = tapiNepRefList.stream()
                    .filter(nepRef::equals)
                    .findFirst().get();
        } catch (NoSuchElementException e) {
            log.error("Nep not found of {}", nepRef);
            throw e;
        }
        return ret;
    }
@Test(expected = NoSuchElementException.class)
    public void testGetNepRefWithSipIdWhenEmpty() {
        tapiResolver.getNepRef(sipId);
    }