What I mean is to the declare the variable as:
```java
  final Map<String, String> dataSet = ...
```
where you include the key and value type parameters to the generic type Map<K, V> instead of using just Map. There are a number of non-subtle implications and pitfal of leaving out the type parameters, besides the fact that you need to cast to String everywhere you use this map.

I hope it makes sort of sense.