How to configure refreshVersions to skip Gradle RC and beta releases and only mention the GA releases

Trying to configure refreshVersions to not mention Gradle RC updates, but it seems that the configuration 

```
refreshVersions {
    rejectVersionIf {
        candidate.stabilityLevel.isLessStableThan(current.stabilityLevel)
    }
}
```
is not related to Gradle updates as I continue to receive notifications about RC availability