Don't synchronize with the main thread when registering async listeners

ProtocolLib/src/main/java/com/comphenix/protocol/async/NullPacketListener.java

@@ -19,6 +19,7 @@ package com.comphenix.protocol.async;
 
 import org.bukkit.plugin.Plugin;
 
+import com.comphenix.protocol.events.ListenerOptions;
 import com.comphenix.protocol.events.ListenerPriority;
 import com.comphenix.protocol.events.ListeningWhitelist;
 import com.comphenix.protocol.events.PacketEvent;
@@ -67,7 +68,8 @@ class NullPacketListener implements PacketListener {
 	
 	private ListeningWhitelist cloneWhitelist(ListenerPriority priority, ListeningWhitelist whitelist) {
 		if (whitelist != null) 
-			return ListeningWhitelist.newBuilder(whitelist).priority(priority).build();
+			// We don't use the Bukkit API, so don't engage the ProtocolLib synchronization code
+			return ListeningWhitelist.newBuilder(whitelist).priority(priority).mergeOptions(ListenerOptions.ASYNC).build();
 		else 
 			return null;
 	}

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

@@ -420,7 +420,6 @@ public class ListeningWhitelist {
 		public Builder gamePhaseBoth() {
 			return gamePhase(GamePhase.BOTH);
 		}
-		
 		/**
 		 * Set the options to copy when constructing new whitelists.
 		 * @param options - the options.
@@ -431,6 +430,16 @@ public class ListeningWhitelist {
 			return this;
 		}
 		
+		/**
+		 * Set the options to copy when constructing new whitelists.
+		 * @param options - the options.
+		 * @return This builder, for chaining.
+		 */
+		public Builder options(Collection<ListenerOptions> options) {
+			this.options = safeSet(options);
+			return this;
+		}
+		
 		/**
 		 * Set the options to copy when constructing new whitelists.
 		 * @param options - the options array.
@@ -441,6 +450,29 @@ public class ListeningWhitelist {
 			return this;
 		}
 		
+		/**
+		 * Options to merge into the current set of options.
+		 * @param options - the options array.
+		 * @return This builder, for chaining.
+		 */
+		public Builder mergeOptions(ListenerOptions... serverOptions) {
+			return mergeOptions(Arrays.asList(serverOptions));
+		}
+		
+		/**
+		 * Options to merge into the current set of options.
+		 * @param options - the options array.
+		 * @return This builder, for chaining.
+		 */
+		public Builder mergeOptions(Collection<ListenerOptions> serverOptions) {
+			if (options == null)
+				return options(serverOptions);
+			
+			// Merge the options
+			this.options.addAll(serverOptions);
+			return this;
+		}
+		
 		/**
 		 * Construct a new whitelist from the values in this builder.
 		 * @return The new whitelist.