public Set<InstanceRedoData> findInstanceRedoData() {
        Set<InstanceRedoData> result = new HashSet<>();
        synchronized (registeredInstances) {
            for (InstanceRedoData each : registeredInstances.values()) {
                if (each.isNeedRedo()) {
                    result.add(each);
                }
            }
        }
        return result;
    }
@Test
    void testFindInstanceRedoData() {
        redoService.cacheInstanceForRedo(SERVICE, GROUP, new Instance());
        assertFalse(redoService.findInstanceRedoData().isEmpty());
        redoService.instanceRegistered(SERVICE, GROUP);
        assertTrue(redoService.findInstanceRedoData().isEmpty());
        redoService.instanceDeregister(SERVICE, GROUP);
        assertFalse(redoService.findInstanceRedoData().isEmpty());
    }