Maybe null wasn't smart

src/main/java/io/gitlab/jfronny/translater/translation/EmptyBackend.java

@@ -12,16 +12,18 @@ public class EmptyBackend implements ITranslationBackend<Object> {
 
     @Override
     public Object detect(String text) {
-        return null;
+        return "null";
     }
 
     @Override
     public Object parseLang(String lang) {
-        return null;
+        return "null";
     }
 
     @Override
     public Collection<Object> getLanguages() {
-        return new HashSet<>();
+        HashSet<Object> set = new HashSet<>();
+        set.add("null");
+        return set;
     }
 }