Remove warning for void GET methods

Jersey logs following WARNING for void GET methods:

```
WARNING: The following warnings have been detected: HINT: A HTTP GET method, public void SomeResource.get(java.lang.String), returns a void type. It can be intentional and perfectly fine, but it is a little uncommon that GET method returns always "204 No Content".
```

Is this really necessary? As the message states a 204 can be perfectly fine for a GET method so I wouldn't classify this as WARNING.

The MVC-Specification (JSR-371) defines a [@View](https://java.net/projects/mvc-spec/sources/git/content/api/src/main/java/javax/mvc/annotation/View.java?rev=99a78604237b10a6eec2b945fa7aa04e8031bf38) annotation which can be used for void methods so this warning will confuse a lot of developers.

Start by locating the Jersey validation or warning path that reports void HTTP GET methods, then inspect how a void return type is classified. Compare that behavior with the issue's example and the referenced @View annotation; done means intentional void GET methods no longer produce a WARNING while other relevant validation remains intact.

Written by the indexing model from the issue text.