public String getInstanceIdGenerator() {
        return getMetaDataByKeyWithDefault(PreservedMetadataKeys.INSTANCE_ID_GENERATOR,
                Constants.DEFAULT_INSTANCE_ID_GENERATOR);
    }
@Test
    void testGetInstanceIdGenerator() {
        Instance instance = new Instance();
        assertEquals(Constants.DEFAULT_INSTANCE_ID_GENERATOR, instance.getInstanceIdGenerator());
        instance.addMetadata(PreservedMetadataKeys.INSTANCE_ID_GENERATOR, "test");
        assertEquals("test", instance.getInstanceIdGenerator());
    }