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.

return new URL(protocol, username, password, host, port, path, getParameters());
    }
    public String getBackupAddress() {
        return getBackupAddress(0);
    }
    public String getBackupAddress(int defaultPort) {
        StringBuilder address = new StringBuilder(appendDefaultPort(getAddress(), defaultPort));
        String[] backups = getParameter(RemotingConstants.BACKUP_KEY, new String[0]);
        if (ArrayUtils.isNotEmpty(backups)) {
            for (String backup : backups) {
                address.append(',');
                address.append(appendDefaultPort(backup, defaultPort));
            }
        }
        return address.toString();
    }
    public List<URL> getBackupUrls() {
        List<URL> urls = new ArrayList<>();
        urls.add(this);
        String[] backups = getParameter(RemotingConstants.BACKUP_KEY, new String[0]);
        if (backups != null && backups.length > 0) {
            for (String backup : backups) {
                urls.add(this.setAddress(backup));
            }
        }
        return urls;
    }
    public String getPath() {
        return path;
    }