#6256: Fixed Watcher copy method for JDK11

Mage/src/test/java/mage/WatcherTest.java

@@ -1,4 +1,73 @@
 package mage;
 
+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.Map;
+import java.util.Set;
+import mage.constants.WatcherScope;
+import mage.game.Game;
+import mage.game.events.GameEvent;
+import mage.watchers.Watcher;
+import org.junit.Test;
+
 public class WatcherTest {
+
+  @Test
+  public void test() {
+    // Given
+    TestWatcher testWatcher = new TestWatcher(GAME);
+    testWatcher.setStringField("stringField");
+    testWatcher.setSetField(ImmutableSet.of("setField1, setField2"));
+    testWatcher.setMapField(ImmutableMap.of("mapFieldKey1, mapFieldValue1", "mapFieldKey2, mapFieldValue2"));
+
+    // When
+    TestWatcher copy = testWatcher.copy();
+
+    // Then
+    assertEquals(testWatcher.getStringField(), copy.getStringField());
+    assertEquals(testWatcher.getSetField(), copy.getSetField());
+    assertEquals(testWatcher.getMapField(), copy.getMapField());
+  }
+
+  public static class TestWatcher extends Watcher {
+    private String stringField;
+    private Set<String> setField;
+    private Map<String, String> mapField;
+
+    public TestWatcher(WatcherScope scope) {
+      super(scope);
+    }
+
+    @Override
+    public void watch(GameEvent event, Game game) {
+      System.out.println("watch");
+    }
+
+    public String getStringField() {
+      return stringField;
+    }
+
+    public void setStringField(String stringField) {
+      this.stringField = stringField;
+    }
+
+    public Set<String> getSetField() {
+      return setField;
+    }
+
+    public void setSetField(Set<String> setField) {
+      this.setField = setField;
+    }
+
+    public Map<String, String> getMapField() {
+      return mapField;
+    }
+
+    public void setMapField(Map<String, String> mapField) {
+      this.mapField = mapField;
+    }
+  }
 }