Changed PR based on Oblique's comments.

Also Added .db-journal to git ignore (file created by a 3d party SQLite GUI program)

.gitignore

@@ -9,3 +9,4 @@
 packets.txt
 log.txt
 /target/
+*.db-journal

scripts/commands/generic/endduel.js

@@ -5,6 +5,8 @@ function executeCommand(galacticManager, player, target, args) {
 	
 	if (player.getCreatureObject().sentDuelRequestToPlayer(target) && !player.getCreatureObject().isInDuelWithPlayer(target)) {
 		new DuelPlayerIntent(player.getCreatureObject(), target, DuelEventType.CANCEL).broadcast();
+	} else if (target.getSentDuelRequestToPlayer(player.getCreatureObject()) && !player.getCreatureObject.sentDuelRequestToPlayer(target)) {
+		new DuelPlayerIntent(player.getCreatureObject(), target, DuelEventType.DECLINE).broadcast();
 	} else {
 		new DuelPlayerIntent(player.getCreatureObject(), target, DuelEventType.END).broadcast();
 	}

src/resources/objects/creature/CreatureObject.java

@@ -30,6 +30,7 @@ package resources.objects.creature;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.List;
 import java.util.Set;
 import java.util.Locale;
 import java.util.function.Predicate;
@@ -79,13 +80,13 @@ public class CreatureObject extends TangibleObject {
 	private long 	statesBitmask			= 0;
 	private long	lastTransform			= 0;
 	
-	private SWGSet<String>		skills				= new SWGSet<String>(1, 3, StringType.ASCII);
+	private SWGSet<String> skills					= new SWGSet<String>(1, 3, StringType.ASCII);
 	
-	private SWGList<Integer>	baseAttributes		= new SWGList<Integer>(1, 2);
+	private SWGList<Integer> baseAttributes			= new SWGList<Integer>(1, 2);
 	
-	private ArrayList<CreatureObject> activeDuels	= new ArrayList<CreatureObject>();
+	private List<CreatureObject> activeDuels		= new ArrayList<>();
 	
-	private ArrayList<CreatureObject> sentDuels		= new ArrayList<CreatureObject>();
+	private List<CreatureObject> sentDuels			= new ArrayList<>();
 	
 	public CreatureObject(long objectId) {
 		super(objectId, BaselineType.CREO);
@@ -810,11 +811,11 @@ public class CreatureObject extends TangibleObject {
 		return activeDuels.contains(player);
 	}
 	
-	public ArrayList<CreatureObject> getActiveDuels() {
+	public List<CreatureObject> getActiveDuels() {
 		return activeDuels;
 	}
 	
-	public ArrayList<CreatureObject> getSentDuels() {
+	public List<CreatureObject> getSentDuels() {
 		return sentDuels;
 	}
 	

src/services/combat/DuelPlayerService.java

@@ -25,7 +25,6 @@
  * along with Holocore.  If not, see <http://www.gnu.org/licenses/>.                *
  *                                                                                  *
  ***********************************************************************************/
-
 package services.combat;
 
 import intents.chat.ChatBroadcastIntent;
@@ -86,7 +85,9 @@ public class DuelPlayerService extends Service {
 	}
 	
 	private void handleDeclineDuel(CreatureObject decliner, CreatureObject target) {
-		// TODO: Implement
+		target.getSentDuels().remove(decliner);
+		sendSystemMessage(decliner, target, "reject_self");
+		sendSystemMessage(target, decliner, "reject_target");
 	}
 	
 	private void handleRequestDuel(CreatureObject requester, CreatureObject target) {