Notify users of PacketListener about async server events.

ProtocolLib/src/main/java/com/comphenix/protocol/events/PacketListener.java

@@ -32,8 +32,10 @@ public interface PacketListener {
 	 * <p>
 	 * Note that the packet may be replaced, if needed.
 	 * <p>
-	 * This method is executed on the main thread, and thus the Bukkit API is safe to use.
+	 * This method is executed on the main thread in 1.6.4 and earlier, and thus the Bukkit API is safe to use.
-	 * 
+	 * <p>
+	 * <b>Warning:</b> In 1.7.2 and later, login and status packets are executed on a worker thread. 
+	 * Call {@link PacketEvent#isAsync()} to detect this in your listener.
 	 * @param event - the packet that should be sent.
 	 */
 	public void onPacketSending(PacketEvent event);