Using unicode character in a (resourcebundle) properties file

Question

I want this text to be printed into the run log:

loadedLanguage = Det laddade språket är sv_SE.

But in the log it turns into

Det laddade språket är sv_SE.

So I´m wondering, how do I use unicode characters inside my properties file? This is the code that loads and prints the text:

ResourceBundle messages = ResourceBundle.getBundle("assets.pokemon.lang.loading", currentLocale);
    log(messages.getString("loadedLanguage"));