I have a simple question but the google and stackoverflow results didn't satisfy me at all.

How can I define a Constants class like:

```
public class Constants {
    public static final int SYSTEM_USER_ID = 1;
}

```

that can be called *everywhere* with **`Constants.SYSTEM_USER_ID`**

I tried it in `grails-app/utils` and `src/java` but for example I couldn't access inside a Service class.