list.size > 0 changed to !list.isEmpty

We care about if it's empty or not, not about it's size

Mage/src/main/java/mage/abilities/costs/CostsImpl.java

@@ -152,7 +152,7 @@ public class CostsImpl<T extends Cost> extends ArrayList<T> implements Costs<T>
 
     protected T getFirstUnpaid() {
         Costs<T> unpaid = getUnpaid();
-        if (unpaid.size() > 0) {
+        if (!unpaid.isEmpty()) {
             return unpaid.get(0);
         }
         return null;