@Override
    public Map<String, Set<String>> getAllIndexAliases() {
        final Map<String, Set<String>> indexNamesAndAliases = indices.getIndexNamesAndAliases(getIndexWildcard());

        // filter out the restored archives from the result set
        return indexNamesAndAliases.entrySet().stream()
                .filter(e -> isGraylogDeflectorIndex(e.getKey()))
                .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
    }
@Test
    public void nullIndexerDoesNotThrow() {
        final Map<String, Set<String>> deflectorIndices = mongoIndexSet.getAllIndexAliases();
        assertThat(deflectorIndices).isEmpty();
    }