From f86529bbb92c74bbb99fa53779264158174e0d26 Mon Sep 17 00:00:00 2001
From: Antonio Alonzi <aalonzi@ebay.com>
Date: Mon, 30 Mar 2020 09:17:07 +0100
Subject: [PATCH] #6256: Do not create new Set/Map

---
 Mage/src/main/java/mage/watchers/Watcher.java |  6 ++--
 Mage/src/test/java/mage/WatcherTest.java      | 31 ++++++++++++++-----
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/Mage/src/main/java/mage/watchers/Watcher.java b/Mage/src/main/java/mage/watchers/Watcher.java
index a3f050aa0d5..762514ec549 100644
--- a/Mage/src/main/java/mage/watchers/Watcher.java
+++ b/Mage/src/main/java/mage/watchers/Watcher.java
@@ -112,11 +112,11 @@ public abstract class Watcher implements Serializable {
 
                     field.setAccessible(true);
                     if (field.getType() == Set.class) {
-                        field.set(watcher, new HashSet<>());
+                        ((Set) field.get(watcher)).clear();
                         ((Set) field.get(watcher)).addAll((Set) field.get(this));
                     } else if (field.getType() == Map.class) {
-                        HashMap<Object, Object> target = new HashMap<>();
-                        field.set(watcher, target);
+                        Map target = ((Map) field.get(watcher));
+                        target.clear();
                         Map source = (Map) field.get(this);
 
                         ParameterizedType parameterizedType = (ParameterizedType) field.getGenericType();
diff --git a/Mage/src/test/java/mage/WatcherTest.java b/Mage/src/test/java/mage/WatcherTest.java
index 45e50a84e34..8ad06fde915 100644
--- a/Mage/src/test/java/mage/WatcherTest.java
+++ b/Mage/src/test/java/mage/WatcherTest.java
@@ -4,9 +4,12 @@ import static mage.constants.WatcherScope.GAME;
 import static org.junit.Assert.assertEquals;
 
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableSet;
+import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 import mage.constants.WatcherScope;
 import mage.game.Game;
 import mage.game.events.GameEvent;
@@ -18,24 +21,36 @@ public class WatcherTest {
   @Test
   public void test() {
     // Given
+    Map<String, String> mapField = new HashMap<>();
+    mapField.put("mapFieldKey1", "mapFieldValue1");
+    mapField.put("mapFieldKey2", "mapFieldValue2");
+
     TestWatcher testWatcher = new TestWatcher(GAME);
     testWatcher.setStringField("stringField");
-    testWatcher.setSetField(ImmutableSet.of("setField1, setField2"));
-    testWatcher.setMapField(ImmutableMap.of("mapFieldKey1, mapFieldValue1", "mapFieldKey2, mapFieldValue2"));
+    testWatcher.setSetField(set("setField1", "setField2"));
+    testWatcher.setMapField(mapField);
 
     // When
     TestWatcher copy = testWatcher.copy();
 
+    // And
+    testWatcher.getSetField().add("setField3");
+    mapField.put("mapFieldKey3", "mapFieldValue3");
+
     // Then
-    assertEquals(testWatcher.getStringField(), copy.getStringField());
-    assertEquals(testWatcher.getSetField(), copy.getSetField());
-    assertEquals(testWatcher.getMapField(), copy.getMapField());
+    assertEquals("stringField", copy.getStringField());
+    assertEquals(set("setField1", "setField2"), copy.getSetField());
+    assertEquals(ImmutableMap.of("mapFieldKey1", "mapFieldValue1", "mapFieldKey2", "mapFieldValue2"), copy.getMapField());
+  }
+
+  private Set<String> set(String... values) {
+    return Stream.of(values).collect(Collectors.toSet());
   }
 
   public static class TestWatcher extends Watcher {
     private String stringField;
-    private Set<String> setField;
-    private Map<String, String> mapField;
+    private Set<String> setField = new HashSet<>();
+    private Map<String, String> mapField = new HashMap<>();
 
     public TestWatcher(WatcherScope scope) {
       super(scope);