mesosphere/marathon — pull request #505 by ConnorDoyle (2014-08-28 00:18:51+00:00)
Title: Group and app names in groups validation error.

Yields

```
HTTP/1.1 422
Content-Type: application/json
Server: Jetty(8.y.z-SNAPSHOT)
Transfer-Encoding: chunked

{
"errors": [
{
"attribute": "apps",
"error": "Groups may contain apps or groups but not both! Apps: [/inky-default] Groups: [/test]"
}
]
}
```