Ensure the modification count is checked correctly

Fixes #202

Author: dmulloy2

modules/API/src/main/java/com/comphenix/protocol/injector/netty/NettyProtocolRegistry.java

@@ -40,7 +40,7 @@ public NettyProtocolRegistry() {
 
 	@Override
 	protected synchronized void initialize() {
-		ProtocolLogger.debug("NettyProtocolRegistry#initialize()"); // Debug for issue #202
+		ProtocolLogger.debug("Initializing the Netty protocol registry"); // Debug for issue #202
 
 		Object[] protocols = enumProtocol.getEnumConstants();
 

modules/API/src/main/java/com/comphenix/protocol/injector/netty/ProtocolRegistry.java

@@ -19,7 +19,7 @@
  * Represents a way of accessing the new netty Protocol enum.
  * @author Kristian
  */
-// TODO: Handle modifications to the BiMap
+
 public abstract class ProtocolRegistry {
 	/**
 	 * Represents a register we are currently building.
@@ -97,7 +97,7 @@ public Set<PacketType> getServerPackets() {
 	 * This operation may block the calling thread.
 	 */
 	public synchronized void synchronize() {
-		// See if the register is outdated
+		// Check if the packet registry has changed
 		if (register.isOutdated()) {
 			initialize();
 		}

modules/API/src/main/java/com/comphenix/protocol/injector/packet/MapContainer.java

@@ -3,24 +3,28 @@
 import java.lang.reflect.Field;
 
 import com.comphenix.protocol.reflect.FieldUtils;
+import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
  * Represents a class that can detect if a map has changed.
  * @author Kristian
  */
 public class MapContainer {
 	// For detecting changes
-	private Field modCountField;
+	private final Field modCountField;
 	private int lastModCount;
 
 	// The object along with whether or not this is the initial run
-	private Object source;
+	private final Object source;
 	private boolean changed;
 
 	public MapContainer(Object source) {
 		this.source = source;
-		this.changed = true;
-		this.modCountField = FieldUtils.getField(source.getClass(), "modCount", true);
+		this.changed = false;
+		
+		Field modCountField = FieldUtils.getField(source.getClass(), "modCount", true);
+		this.modCountField = checkNotNull(modCountField, "Could not obtain modCount field");
+		this.lastModCount = getModificationCount();
 	}
 
 	/**
@@ -55,13 +59,13 @@ protected void checkChanged() {
 
 	/**
 	 * Retrieve the current modification count.
-	 * @return The current count, or something different than lastModCount if not accessible.
+	 * @return The current count
 	 */
 	private int getModificationCount() {
 		try {
-			return modCountField != null ? modCountField.getInt(source) : lastModCount + 1;
-		} catch (Exception e) {
-			throw new RuntimeException("Unable to retrieve modCount.", e);
+			return modCountField.getInt(source);
+		} catch (ReflectiveOperationException ex) {
+			throw new RuntimeException("Unable to retrieve modCount.", ex);
 		}
 	}
 }