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.

}
    }
    private String buildString(boolean appendUser, boolean appendParameter, String... parameters) {
        return buildString(appendUser, appendParameter, false, false, parameters);
    }
    private String buildString(boolean appendUser, boolean appendParameter, boolean useIP, boolean useService, String... parameters) {
        StringBuilder buf = new StringBuilder();
        if (StringUtils.isNotEmpty(protocol)) {
            buf.append(protocol);
            buf.append("://");
        }
        if (appendUser && StringUtils.isNotEmpty(username)) {
            buf.append(username);
            if (StringUtils.isNotEmpty(password)) {
                buf.append(":");
                buf.append(password);
            }
            buf.append("@");
        }
        String host;
        if (useIP) {
            host = getIp();
        } else {
            host = getHost();
        }
        if (StringUtils.isNotEmpty(host)) {
            buf.append(host);
            if (port > 0) {
                buf.append(":");
                buf.append(port);