public Map<String, Object> getPrefix(String key) {
        var map = new HashMap<String, Object>();
        if (null != key) {
            props.forEach((key_, value) -> {
                if (key_.toString().startsWith(key)) {
                    map.put(key_.toString().substring(key.length() + 1), value);
                }
            });
        }
        return map;
    }
@Test
    public void testGetPrefix() {
        Environment environment = Environment.of("application.properties");
        Map<String, Object> map = environment.getPrefix("app");
        assertEquals(7, map.size());
        assertEquals("0.0.2", map.get("version"));
    }