uid collision on Centos 7 host

The hard-coded uid=999 value conflicts with the systemd-bus-proxy user on CentOS 7
```
$ grep :999: /etc/passwd
systemd-bus-proxy:x:999:997:systemd Bus Proxy:/:/sbin/nologin
```

This makes it difficult to use a volume mapped to a host directory as it is owned by the above user.   Is there a recommended way to handle this?