Auto-unboxing :). 
If I want to set an ```int``` property using a mapper method with the following signature, the first type check above there would fail, as T is not assibnable to int:
```public <T> T convert(String string, @MappingTargetType Class<T> clazz) { ... }```
At least that's what I was experiencing in the unit tests. But I'll double check if it is still needed in the current state.