add method Game.isActivePlayer(UUID playerId)

Mage/src/main/java/mage/abilities/PlayLandAbility.java

@@ -31,7 +31,7 @@ public class PlayLandAbility extends ActivatedAbilityImpl {
             return ActivationStatus.getFalse();
         }
         //20091005 - 114.2a
-        return new ActivationStatus(game.getActivePlayerId().equals(playerId) && game.getPlayer(playerId).canPlayLand() && game.canPlaySorcery(playerId), permittingObject);
+        return new ActivationStatus(game.isActivePlayer(playerId) && game.getPlayer(playerId).canPlayLand() && game.canPlaySorcery(playerId), permittingObject);
     }
 
     @Override

Mage/src/main/java/mage/abilities/effects/common/HideawayPlayEffect.java

@@ -51,7 +51,7 @@ public class HideawayPlayEffect extends OneShotEffect {
                  */
                 if (card.isLand()) {
                     UUID playerId = controller.getId();
-                    if (!game.getActivePlayerId().equals(playerId) || !game.getPlayer(playerId).canPlayLand()) {
+                    if (!game.isActivePlayer(playerId) || !game.getPlayer(playerId).canPlayLand()) {
                         return false;
                     }
                 }

Mage/src/main/java/mage/abilities/mana/ManaOptions.java

@@ -154,7 +154,7 @@ public class ManaOptions extends ArrayList<Mana> {
                         }
                     }
                 }
-            } else if (abilities.size() > 1) {
+            } else {
                 //perform a union of all existing options and the new options
                 List<Mana> copy = copy();
                 this.clear();
@@ -227,7 +227,7 @@ public class ManaOptions extends ArrayList<Mana> {
             if (options.size() == 1) {
                 //if there is only one mana option available add it to all the existing options
                 addMana(options.get(0));
-            } else if (options.size() > 1) {
+            } else {
                 //perform a union of all existing options and the new options
                 List<Mana> copy = copy();
                 this.clear();

Mage/src/main/java/mage/game/Game.java

@@ -3,6 +3,8 @@ package mage.game;
 
 import java.io.Serializable;
 import java.util.*;
+import java.util.stream.Collectors;
+
 import mage.MageItem;
 import mage.MageObject;
 import mage.abilities.Ability;
@@ -119,15 +121,17 @@ public interface Game extends MageItem, Serializable {
      * @param playerId
      * @return
      */
-    default public Set<UUID> getOpponents(UUID playerId) {
-        Set<UUID> opponents = new HashSet<>();
+    default Set<UUID> getOpponents(UUID playerId) {
         Player player = getPlayer(playerId);
-        for (UUID opponentId : player.getInRange()) {
-            if (!opponentId.equals(playerId)) {
-                opponents.add(opponentId);
-            }
-        }
-        return opponents;
+        return player.getInRange().stream()
+                .filter(opponentId -> !opponentId.equals(playerId))
+                .collect(Collectors.toSet());
+
+    }
+
+
+    default boolean isActivePlayer(UUID playerId){
+        return getActivePlayerId().equals(playerId);
     }
 
     /**
@@ -141,7 +145,7 @@ public interface Game extends MageItem, Serializable {
      * @param playerToCheckId
      * @return
      */
-    default public boolean isOpponent(Player player, UUID playerToCheckId) {
+    default boolean isOpponent(Player player, UUID playerToCheckId) {
         return !player.getId().equals(playerToCheckId);
     }
 

Mage/src/main/java/mage/game/GameImpl.java

@@ -2450,7 +2450,7 @@ public abstract class GameImpl implements Game, Serializable {
 
     @Override
     public boolean canPlaySorcery(UUID playerId) {
-        return isMainPhase() && getActivePlayerId().equals(playerId) && getStack().isEmpty();
+        return isMainPhase() && isActivePlayer(playerId) && getStack().isEmpty();
     }
 
     /**
@@ -2594,7 +2594,7 @@ public abstract class GameImpl implements Game, Serializable {
         // If the current monarch leaves the game. When that happens, the player whose turn it is becomes the monarch.
         // If the monarch leaves the game on their turn, the next player in turn order becomes the monarch.
         if (playerId.equals(getMonarchId())) {
-            if (!getActivePlayerId().equals(playerId)) {
+            if (!isActivePlayer(playerId)) {
                 setMonarchId(null, getActivePlayerId());
             } else {
                 Player nextPlayer = getPlayerList().getNext(this);

Mage/src/main/java/mage/players/PlayerImpl.java

@@ -2956,9 +2956,7 @@ public abstract class PlayerImpl implements Player, Serializable {
                 // Other activated abilities
                 LinkedHashMap<UUID, ActivatedAbility> useable = new LinkedHashMap<>();
                 getOtherUseableActivatedAbilities(card, Zone.GRAVEYARD, game, useable);
-                for (Ability ability : useable.values()) {
-                    playable.add(ability);
-                }
+                playable.addAll(useable.values());
             }
             for (ExileZone exile : game.getExile().getExileZones()) {
                 for (Card card : exile.getCards(game)) {

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

@@ -76,7 +76,7 @@ public class PermanentsEnteredBattlefieldYourLastTurnWatcher extends Watcher {
     }
 
     public List<Permanent> getPermanentsEnteringOnPlayersLastTurn(Game game, UUID playerId) {
-        if (game.getActivePlayerId().equals(playerId)) {
+        if (game.isActivePlayer(playerId)) {
             return enteringBattlefield.get(playerId);
         }
         return enteringBattlefieldLastTurn.get(playerId);