Reduce use of expensive getTransporting(). (#11913)

* Reduce use of expensive getTransporting().

* Remove now unnecessary stubbing.

* Removed unused imports.

game-app/game-core/src/main/java/games/strategy/triplea/delegate/MovePerformer.java

@@ -385,10 +385,13 @@ private void markTransportsMovement(
     final boolean paratroopsLanding =
         arrived.stream().anyMatch(paratroopNAirTransports)
             && MoveValidator.allLandUnitsAreBeingParatroopered(arrived);
-    final Map<Unit, Collection<Unit>> dependentAirTransportableUnits =
-        new HashMap<>(
-            MoveValidator.getDependents(
-                CollectionUtils.getMatches(arrived, Matches.unitCanTransport())));
+    final Map<Unit, Collection<Unit>> dependentAirTransportableUnits = new HashMap<>();
+    for (final Unit unit : arrived) {
+      Unit transport = unit.getTransportedBy();
+      if (transport != null) {
+        dependentAirTransportableUnits.computeIfAbsent(transport, u -> new ArrayList<>()).add(unit);
+      }
+    }
     // add newly created dependents
     for (final Entry<Unit, Collection<Unit>> entry : airTransportDependents.entrySet()) {
       Collection<Unit> dependents = dependentAirTransportableUnits.get(entry.getKey());
@@ -414,7 +417,7 @@ private void markTransportsMovement(
       // mark transports as having transported
       for (final Unit load : transporting.keySet()) {
         final Unit transport = transporting.get(load);
-        if (!transport.getTransporting().contains(load)) {
+        if (!transport.equals(load.getTransportedBy())) {
           final Change change = TransportTracker.loadTransportChange(transport, load);
           currentMove.addChange(change);
           currentMove.load(transport);

game-app/game-core/src/main/java/games/strategy/triplea/delegate/move/validation/MoveValidator.java

@@ -865,17 +865,12 @@ private static Collection<Unit> findNonDependentUnits(
       final Collection<Unit> units,
       final Route route,
       final Map<Unit, Collection<Unit>> airTransportDependents) {
-    final Map<Unit, Collection<Unit>> dependentsMap =
-        getDependents(CollectionUtils.getMatches(units, Matches.unitCanTransport()));
-    final Set<Unit> dependents =
-        dependentsMap.values().stream().flatMap(Collection::stream).collect(Collectors.toSet());
-    dependents.addAll(
-        airTransportDependents.values().stream()
-            .flatMap(Collection::stream)
-            .collect(Collectors.toSet()));
     final Collection<Unit> unitsWithoutDependents = new ArrayList<>();
     unitsWithoutDependents.addAll(route.getStart().isWater() ? getNonLand(units) : units);
-    unitsWithoutDependents.removeAll(dependents);
+    unitsWithoutDependents.removeIf(u -> u.getTransportedBy() != null);
+    for (Collection<Unit> deps : airTransportDependents.values()) {
+      unitsWithoutDependents.removeAll(deps);
+    }
     return unitsWithoutDependents;
   }
 
@@ -943,15 +938,6 @@ private static IntegerMap<Unit> getLandTransportsWithCapacity(
     return map;
   }
 
-  public static Map<Unit, Collection<Unit>> getDependents(final Collection<Unit> units) {
-    // just worry about transports
-    final Map<Unit, Collection<Unit>> dependents = new HashMap<>();
-    for (final Unit unit : units) {
-      dependents.put(unit, unit.getTransporting());
-    }
-    return dependents;
-  }
-
   /**
    * Checks that there are no enemy units on the route except possibly at the end. Submerged enemy
    * units are not considered as they don't affect movement. AA and factory dont count as enemy.

game-app/game-core/src/test/java/games/strategy/triplea/delegate/battle/steps/retreat/DefensiveSubsRetreatTest.java

@@ -1,6 +1,5 @@
 package games.strategy.triplea.delegate.battle.steps.retreat;
 
-import static games.strategy.triplea.Constants.UNIT_ATTACHMENT_NAME;
 import static games.strategy.triplea.delegate.battle.BattleState.Side.DEFENSE;
 import static games.strategy.triplea.delegate.battle.FakeBattleState.givenBattleStateBuilder;
 import static games.strategy.triplea.delegate.battle.steps.BattleStepsTest.givenUnitCanEvade;
@@ -28,7 +27,6 @@
 import games.strategy.engine.delegate.IDelegateBridge;
 import games.strategy.engine.display.IDisplay;
 import games.strategy.engine.history.IDelegateHistoryWriter;
-import games.strategy.triplea.attachments.UnitAttachment;
 import games.strategy.triplea.delegate.ExecutionStack;
 import games.strategy.triplea.delegate.battle.BattleActions;
 import games.strategy.triplea.delegate.battle.BattleState;
@@ -225,9 +223,6 @@ void retreatHappensWhenNotSubmersibleButHasRetreatTerritories() {
       final GameData gameData = givenGameData().build();
 
       final Unit unit = givenRealUnitCanEvade(gameData, defender);
-      final UnitAttachment unitAttachment =
-          (UnitAttachment) unit.getType().getAttachment(UNIT_ATTACHMENT_NAME);
-      when(unitAttachment.getTransportCapacity()).thenReturn(-1);
       final Collection<Unit> retreatingUnits = List.of(unit);
 
       final Territory retreatTerritory = mock(Territory.class);
@@ -265,7 +260,6 @@ void retreatHappensWhenNotSubmersibleButHasRetreatTerritories() {
 
     @Test
     void retreatHappensWhenDefendingIsSubmersibleAndHasRetreatTerritories() {
-
       final Territory retreatTerritory = mock(Territory.class);
       when(retreatTerritory.isWater()).thenReturn(true);
       final UnitCollection retreatTerritoryCollection = mock(UnitCollection.class);
@@ -280,9 +274,6 @@ void retreatHappensWhenDefendingIsSubmersibleAndHasRetreatTerritories() {
               .build();
 
       final Unit unit = givenRealUnitCanEvade(gameData, defender);
-      final UnitAttachment unitAttachment =
-          (UnitAttachment) unit.getType().getAttachment(UNIT_ATTACHMENT_NAME);
-      when(unitAttachment.getTransportCapacity()).thenReturn(-1);
       final Collection<Unit> retreatingUnits = List.of(unit);
 
       final BattleState battleState =