Behaviour is unused. Stilled mechanic?

src/engine/wpakpowers/Behaviours.java

@@ -53,7 +53,7 @@ public class Behaviours {
 
     public static Object SubTypeSkill(AbstractCharacter caster, Power power, Integer rank, AbstractWorldObject target,
                                       PowerAction powerAction, Effect effect, ModifierEntry modifierEntry) {
-        return modifierEntry.arg1;
+        return null;  // Unused in data
     }
 
     public static Object FPSubTypeDmg(AbstractCharacter caster, Power power, Integer rank, AbstractWorldObject target,