@Override
    public ConfigData get(String path) {
        return get(path, Files::isRegularFile);
    }
@Test
    public void testGetSetOfKeysAtPath() {
        Set<String> keys = toSet(asList(foo, "baz"));
        ConfigData configData = provider.get(dir, keys);
        assertEquals(Collections.singleton(foo), configData.data().keySet());
        assertEquals("FOO", configData.data().get(foo));
        assertNull(configData.ttl());
    }