[OTJ] add test for saddled this turn

Mage/src/main/java/mage/filter/predicate/permanent/SaddledSourceThisTurnPredicate.java

@@ -7,6 +7,8 @@ import mage.game.permanent.Permanent;
 import mage.watchers.common.SaddledMountWatcher;
 
 /**
+ * requires SaddledMountWatcher
+ *
  * @author TheElk801
  */
 public enum SaddledSourceThisTurnPredicate implements ObjectSourcePlayerPredicate<Permanent> {

Mage/src/main/java/mage/watchers/common/SaddledMountWatcher.java

@@ -14,6 +14,7 @@ import java.util.*;
  */
 public class SaddledMountWatcher extends Watcher {
 
+    // key: the mount, value: set of creatures which saddled
     private final Map<MageObjectReference, Set<MageObjectReference>> saddleMap = new HashMap<>();
 
     public SaddledMountWatcher() {