lower version, for example 2.6.8
```properties
dubbo.provider.version=1.0
```

2.7.6 failed to recognize the provider url with 'default.version=1.0' key,  it only takes 'version.1.0' into consideration.

}
        if (PORT_KEY.equals(key)) {
            return String.valueOf(port);
        }
        if (PATH_KEY.equals(key)) {
            return path;
        }
        return getParameter(key);
    }
    public Map<String, String> toMap() {
        Map<String, String> map = new HashMap<>(parameters);
        if (protocol != null) {
            map.put(PROTOCOL_KEY, protocol);
        }
        if (username != null) {
            map.put(USERNAME_KEY, username);
        }
        if (password != null) {
            map.put(PASSWORD_KEY, password);
        }
        if (host != null) {
            map.put(HOST_KEY, host);
        }
        if (port > 0) {
            map.put(PORT_KEY, String.valueOf(port));
        }
        if (path != null) {
            map.put(PATH_KEY, path);
        }
        return map;