Remove some creation of temp empty collections.

game-app/game-core/src/main/java/games/strategy/triplea/ai/pro/ProCombatMoveAi.java

@@ -422,7 +422,7 @@ private void determineTerritoriesThatCanBeHeld(
     }
     final Map<Territory, Double> territoryValueMap =
         ProTerritoryValueUtils.findTerritoryValues(
-            proData, player, new ArrayList<>(), clearedTerritories, territoriesToCheck);
+            proData, player, List.of(), clearedTerritories, territoriesToCheck);
     for (final ProTerritory patd : prioritizedTerritories) {
       final Territory t = patd.getTerritory();
 

game-app/game-core/src/main/java/games/strategy/triplea/ai/pro/ProPurchaseAi.java

@@ -191,7 +191,7 @@ Map<Territory, ProPurchaseTerritory> bid(
       }
       final Map<Territory, Double> territoryValueMap =
           ProTerritoryValueUtils.findTerritoryValues(
-              proData, player, new ArrayList<>(), new ArrayList<>(), territoriesToCheck);
+              proData, player, List.of(), List.of(), territoriesToCheck);
       for (final ProPurchaseTerritory t : purchaseTerritories.values()) {
         for (final ProPlaceTerritory ppt : t.getCanPlaceTerritories()) {
           ppt.setStrategicValue(territoryValueMap.get(ppt.getTerritory()));
@@ -311,7 +311,7 @@ Map<Territory, ProPurchaseTerritory> purchase(
     }
     final Map<Territory, Double> territoryValueMap =
         ProTerritoryValueUtils.findTerritoryValues(
-            proData, player, new ArrayList<>(), new ArrayList<>(), territoriesToCheck);
+            proData, player, List.of(), List.of(), territoriesToCheck);
     for (final Territory t : purchaseTerritories.keySet()) {
       for (final ProPlaceTerritory ppt : purchaseTerritories.get(t).getCanPlaceTerritories()) {
         ppt.setStrategicValue(territoryValueMap.get(ppt.getTerritory()));
@@ -547,7 +547,7 @@ void place(
     }
     final Map<Territory, Double> territoryValueMap =
         ProTerritoryValueUtils.findTerritoryValues(
-            proData, player, new ArrayList<>(), new ArrayList<>(), territoriesToCheck);
+            proData, player, List.of(), List.of(), territoriesToCheck);
     for (final ProPurchaseTerritory t : placeNonConstructionTerritories.values()) {
       for (final ProPlaceTerritory ppt : t.getCanPlaceTerritories()) {
         ppt.setStrategicValue(territoryValueMap.get(ppt.getTerritory()));
@@ -1079,7 +1079,7 @@ private void purchaseLandUnits(
     }
     final Map<Territory, Double> territoryValueMap =
         ProTerritoryValueUtils.findTerritoryValues(
-            proData, player, new ArrayList<>(), new ArrayList<>(), territoriesToCheck);
+            proData, player, List.of(), List.of(), territoriesToCheck);
     for (final ProPlaceTerritory placeTerritory : prioritizedLandTerritories) {
       final Territory t = placeTerritory.getTerritory();
       ProLogger.debug("Checking land place for " + t.getName());
@@ -1332,11 +1332,7 @@ private void purchaseFactory(
     // Find strategic value for each territory
     final Map<Territory, Double> territoryValueMap =
         ProTerritoryValueUtils.findTerritoryValues(
-            proData,
-            player,
-            territoriesThatCantBeHeld,
-            new ArrayList<>(),
-            purchaseFactoryTerritories);
+            proData, player, territoriesThatCantBeHeld, List.of(), purchaseFactoryTerritories);
     double maxValue = 0.0;
     Territory maxTerritory = null;
     for (final Territory t : purchaseFactoryTerritories) {
@@ -1917,7 +1913,7 @@ private boolean purchaseSeaAndAmphibUnits(
       }
       final Map<Territory, Double> territoryValueMap =
           ProTerritoryValueUtils.findTerritoryValues(
-              proData, player, new ArrayList<>(), new ArrayList<>(), territoriesToCheck);
+              proData, player, List.of(), List.of(), territoriesToCheck);
       ProLogger.trace(t + ", transportMovement=" + distance);
       for (final ProPurchaseTerritory purchaseTerritory : selectedPurchaseTerritories) {
         final Territory landTerritory = purchaseTerritory.getTerritory();

game-app/game-core/src/main/java/games/strategy/triplea/ai/pro/data/ProBattleResult.java

@@ -1,8 +1,8 @@
 package games.strategy.triplea.ai.pro.data;
 
 import games.strategy.engine.data.Unit;
-import java.util.ArrayList;
 import java.util.Collection;
+import java.util.List;
 import lombok.AllArgsConstructor;
 import lombok.Getter;
 import lombok.ToString;
@@ -21,6 +21,6 @@ public class ProBattleResult {
   private final double battleRounds;
 
   public ProBattleResult() {
-    this(0, -1, false, new ArrayList<>(), new ArrayList<>(), 0);
+    this(0, -1, false, List.of(), List.of(), 0);
   }
 }

game-app/game-core/src/main/java/games/strategy/triplea/ai/pro/util/ProOddsCalculator.java

@@ -56,7 +56,7 @@ public ProBattleResult estimateAttackBattleResults(
     final double strengthDifference =
         ProBattleUtils.estimateStrengthDifference(t, attackingUnits, defendingUnits);
     if (strengthDifference < 45) {
-      return new ProBattleResult(0, -999, false, new ArrayList<>(), defendingUnits, 1);
+      return new ProBattleResult(0, -999, false, List.of(), defendingUnits, 1);
     }
     return callBattleCalc(proData, t, attackingUnits, defendingUnits, bombardingUnits);
   }
@@ -93,7 +93,7 @@ public ProBattleResult estimateDefendBattleResults(
           999 + strengthDifference,
           !isLandAndCanOnlyBeAttackedByAir,
           attackingUnits,
-          new ArrayList<>(),
+          List.of(),
           1);
     }
     return callBattleCalc(proData, t, attackingUnits, defendingUnits, bombardingUnits);
@@ -179,7 +179,7 @@ private static ProBattleResult checkIfNoAttackersOrDefenders(
           CollectionUtils.getMatches(
               defendingUnits, Matches.unitCanBeInBattle(false, !t.isWater(), 1, true));
       final double tuv = TuvUtils.getTuv(mainCombatDefenders, proData.getUnitValueMap());
-      return new ProBattleResult(100, 0.1 + tuv, true, attackingUnits, new ArrayList<>(), 0);
+      return new ProBattleResult(100, 0.1 + tuv, true, attackingUnits, List.of(), 0);
     } else if (canSubmergeBeforeBattle(
         proData.getData(), attackingUnits, defendingUnits, checkSubmerge)) {
       return new ProBattleResult();

game-app/game-core/src/test/java/games/strategy/engine/data/RouteFinderTest.java

@@ -11,7 +11,6 @@
 
 import com.google.common.base.Preconditions;
 import java.math.BigDecimal;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
@@ -81,7 +80,7 @@ private void configureNeighbors(final Territory territory, final Territory... ne
 
   @Test
   void testFindRoute() {
-    final RouteFinder routeFinder = new RouteFinder(map, t -> true, new ArrayList<>(), player);
+    final RouteFinder routeFinder = new RouteFinder(map, t -> true, List.of(), player);
     final Optional<Route> optRoute =
         routeFinder.findRouteByDistance(
             territories.get(0), territories.get(territories.size() - 1));
@@ -93,7 +92,7 @@ void testFindRoute() {
 
   @Test
   void testFindRouteEndAndStartAreTheSame() {
-    final RouteFinder routeFinder = new RouteFinder(map, t -> true, new ArrayList<>(), player);
+    final RouteFinder routeFinder = new RouteFinder(map, t -> true, List.of(), player);
     final Optional<Route> optRoute =
         routeFinder.findRouteByDistance(territories.get(0), territories.get(0));
     assertTrue(optRoute.isPresent());
@@ -108,8 +107,7 @@ void testNoRouteOnInvalidGraph() {
     final Territory island1 = mock(Territory.class);
     when(islandMap.getNeighbors(eq(island0), any())).thenReturn(Set.of());
 
-    final RouteFinder routeFinder =
-        new RouteFinder(islandMap, t -> true, new ArrayList<>(), player);
+    final RouteFinder routeFinder = new RouteFinder(islandMap, t -> true, List.of(), player);
 
     final Optional<Route> optRoute = routeFinder.findRouteByDistance(island0, island1);
 
@@ -118,7 +116,7 @@ void testNoRouteOnInvalidGraph() {
 
   @Test
   void testFindRouteByCost() {
-    final RouteFinder routeFinder = new RouteFinder(map, t -> true, new ArrayList<>(), player);
+    final RouteFinder routeFinder = new RouteFinder(map, t -> true, List.of(), player);
     final Optional<Route> optRoute =
         routeFinder.findRouteByCost(territories.get(0), territories.get(territories.size() - 1));
     assertTrue(optRoute.isPresent());
@@ -152,8 +150,7 @@ void testFindRouteByCostWithMovementCosts2() {
   }
 
   private RouteFinder createRouteFinder(final List<Territory> territoriesWithIncreasedCost) {
-    final RouteFinder routeFinder =
-        Mockito.spy(new RouteFinder(map, t -> true, new ArrayList<>(), player));
+    final RouteFinder routeFinder = Mockito.spy(new RouteFinder(map, t -> true, List.of(), player));
     doAnswer(
             invocation ->
                 territoriesWithIncreasedCost.contains(invocation.getArgument(0))
@@ -166,7 +163,7 @@ private RouteFinder createRouteFinder(final List<Territory> territoriesWithIncre
 
   @Test
   void testFindRouteByCostEndAndStartAreTheSame() {
-    final RouteFinder routeFinder = new RouteFinder(map, t -> true, new ArrayList<>(), player);
+    final RouteFinder routeFinder = new RouteFinder(map, t -> true, List.of(), player);
     final Optional<Route> optRoute =
         routeFinder.findRouteByCost(territories.get(0), territories.get(0));
     assertTrue(optRoute.isPresent());
@@ -179,7 +176,7 @@ void testNoRouteByCostOnInvalidGraph() {
     final GameMap map = mock(GameMap.class);
     when(map.getNeighbors(eq(territories.get(0)), any())).thenReturn(Set.of(territories.get(1)));
 
-    final RouteFinder routeFinder = new RouteFinder(map, t -> true, new ArrayList<>(), player);
+    final RouteFinder routeFinder = new RouteFinder(map, t -> true, List.of(), player);
     final Optional<Route> optRoute =
         routeFinder.findRouteByCost(territories.get(0), territories.get(territories.size() - 1));
     assertFalse(optRoute.isPresent());

game-app/game-headed/src/main/java/games/strategy/triplea/ui/EditPanel.java

@@ -378,8 +378,7 @@ public void actionPerformed(final ActionEvent event) {
             final MustMoveWithDetails mustMoveWithDetails;
             try (GameData.Unlocker ignored = getData().acquireReadLock()) {
               mustMoveWithDetails =
-                  MoveValidator.getMustMoveWith(
-                      selectedTerritory, new HashMap<>(), getCurrentPlayer());
+                  MoveValidator.getMustMoveWith(selectedTerritory, Map.of(), getCurrentPlayer());
             }
             final boolean mustChoose;
             final List<Unit> allUnits = new ArrayList<>(selectedTerritory.getUnits());