Changed ConcurrentHashMap to a custom SynchronizedHashMap for null value support

src/resources/objects/SWGObject.java

@@ -52,6 +52,7 @@ import resources.persistable.Persistable;
 import resources.persistable.SWGObjectFactory;
 import resources.player.Player;
 import resources.server_info.Log;
+import resources.server_info.SynchronizedHashMap;
 import services.CoreManager;
 import services.objects.ObjectCreator;
 import utilities.AwarenessUtilities;
@@ -65,7 +66,6 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicInteger;
 
 public abstract class SWGObject extends BaselineObject implements Comparable<SWGObject>, Persistable {
@@ -74,7 +74,7 @@ public abstract class SWGObject extends BaselineObject implements Comparable<SWG
 	private final Location 						location		= new Location(0, 0, 0, null);
 	private final Location						buildoutLocation= new Location(0, 0, 0, null);
 	private final Set<SWGObject>				containedObjects= new HashSet<>();
-	private final Map <String, SWGObject>	slots			= new ConcurrentHashMap<>(); // HashMap used for null value support
+	private final Map <String, SWGObject>	slots			= new SynchronizedHashMap<>();
 	private final transient Map <String, String>				attributes		= new LinkedHashMap<>();
 	private final transient ObjectAware							awareness		= new ObjectAware(this);
 	private final transient Map <ObjectDataAttribute, Object>	dataAttributes	= new HashMap<>();

src/resources/server_info/SynchronizedHashMap.java

@@ -0,0 +1,133 @@
+/************************************************************************************
+ * Copyright (c) 2015 /// Project SWG /// www.projectswg.com                        *
+ *                                                                                  *
+ * ProjectSWG is the first NGE emulator for Star Wars Galaxies founded on           *
+ * July 7th, 2011 after SOE announced the official shutdown of Star Wars Galaxies.  *
+ * Our goal is to create an emulator which will provide a server for players to     *
+ * continue playing a game similar to the one they used to play. We are basing      *
+ * it on the final publish of the game prior to end-game events.                    *
+ *                                                                                  *
+ * This file is part of Holocore.                                                   *
+ *                                                                                  *
+ * -------------------------------------------------------------------------------- *
+ *                                                                                  *
+ * Holocore is free software: you can redistribute it and/or modify                 *
+ * it under the terms of the GNU Affero General Public License as                   *
+ * published by the Free Software Foundation, either version 3 of the               *
+ * License, or (at your option) any later version.                                  *
+ *                                                                                  *
+ * Holocore is distributed in the hope that it will be useful,                      *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of                   *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the                    *
+ * GNU Affero General Public License for more details.                              *
+ *                                                                                  *
+ * You should have received a copy of the GNU Affero General Public License         *
+ * along with Holocore.  If not, see <http://www.gnu.org/licenses/>.                *
+ *                                                                                  *
+ ***********************************************************************************/
+package resources.server_info;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
+public class SynchronizedHashMap<K, V> implements Map<K, V> {
+	
+	private final HashMap<K, V> map;
+	
+	public SynchronizedHashMap() {
+		map = new HashMap<>();
+	}
+	
+	public int hashCode() {
+		synchronized (map) {
+			return map.hashCode();
+		}
+	}
+	
+	public String toString() {
+		synchronized (map) {
+			return map.toString();
+		}
+	}
+	
+	public int size() {
+		synchronized (map) {
+			return map.size();
+		}
+	}
+	
+	public boolean isEmpty() {
+		synchronized (map) {
+			return map.isEmpty();
+		}
+	}
+	
+	public V get(Object key) {
+		synchronized (map) {
+			return map.get(key);
+		}
+	}
+	
+	public boolean containsKey(Object key) {
+		synchronized (map) {
+			return map.containsKey(key);
+		}
+	}
+	
+	public V put(K key, V value) {
+		synchronized (map) {
+			return map.put(key, value);
+		}
+	}
+	
+	public void putAll(Map<? extends K, ? extends V> m) {
+		synchronized (map) {
+			map.putAll(m);
+		}
+	}
+	
+	public V remove(Object key) {
+		synchronized (map) {
+			return map.remove(key);
+		}
+	}
+	
+	public void clear() {
+		synchronized (map) {
+			map.clear();
+		}
+	}
+	
+	public boolean containsValue(Object value) {
+		synchronized (map) {
+			return map.containsValue(value);
+		}
+	}
+	
+	public Set<K> keySet() {
+		synchronized (map) {
+			return map.keySet();
+		}
+	}
+	
+	public Collection<V> values() {
+		synchronized (map) {
+			return map.values();
+		}
+	}
+	
+	public Set<java.util.Map.Entry<K, V>> entrySet() {
+		synchronized (map) {
+			return map.entrySet();
+		}
+	}
+	
+	public V replace(K key, V value) {
+		synchronized (map) {
+			return map.replace(key, value);
+		}
+	}
+	
+}