public ErrorStatsData getStats(String route, String cause) {
        Map<String, ErrorStatsData> map = routeMap.get(route);
        if (map == null) {
            return null;
        }
        return map.get(cause);
    }
@Test
    void testGetStats() {
        ErrorStatsManager sm = new ErrorStatsManager();
        assertNotNull(sm);
        sm.putStats("test", "cause");
        assertNotNull(sm.getStats("test", "cause"));
    }