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.

int methodSeparator = key.indexOf('.');
                if (methodSeparator > 0) {
                    String method = key.substring(0, methodSeparator);
                    String realKey = key.substring(methodSeparator + 1);
                    URL.putMethodParameter(method, realKey, entry.getValue(), methodParameters);
                }
            }
        }
        return methodParameters;
    }
    public static URL valueOf(String url, String... reserveParams) {
        URL result = valueOf(url);
        if (reserveParams == null || reserveParams.length == 0) {
            return result;
        }
        Map<String, String> newMap = new HashMap<>(reserveParams.length);
        Map<String, String> oldMap = result.getParameters();
        for (String reserveParam : reserveParams) {
            String tmp = oldMap.get(reserveParam);
            if (StringUtils.isNotEmpty(tmp)) {
                newMap.put(reserveParam, tmp);
            }
        }
        return result.clearParameters().addParameters(newMap);
    }
    public static URL valueOf(URL url, String[] reserveParams, String[] reserveParamPrefixs) {
        Map<String, String> newMap = new HashMap<>();
        Map<String, String> oldMap = url.getParameters();
        if (reserveParamPrefixs != null && reserveParamPrefixs.length != 0) {
            for (Map.Entry<String, String> entry : oldMap.entrySet()) {