char[] are not converted to String when used in templates

When using a `char[]` in a template the output is not correctly converted to String.

For example this:
```html
<div>{{ myCharArray }}</div>
```

```java
@JsProperty char[] charArrayData = new char[]{'a', 'b', 'c'};
```

Is rendered to `97,98,99` instead of `abc`