Clear tab list on server connect

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java

@@ -4,6 +4,7 @@ import com.velocitypowered.api.event.connection.DisconnectEvent;
 import com.velocitypowered.api.event.connection.PluginMessageEvent;
 import com.velocitypowered.api.event.player.PlayerChatEvent;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
+import com.velocitypowered.api.proxy.player.TabList;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.connection.VelocityConstants;
@@ -238,6 +239,10 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
             // The call will handle if the player is not a Forge player appropriately.
             player.getConnection().setCanSendLegacyFMLResetPacket(true);
         } else {
+            // Clear tab list to avoid duplicate entries
+            TabList tabList = player.getTabList();
+            tabList.getEntries().forEach(entry -> tabList.removeEntry(entry.getProfile().idAsUuid()));
+
             // Ah, this is the meat and potatoes of the whole venture!
             //
             // In order to handle switching to another server, you will need to send three packets:

proxy/src/main/java/com/velocitypowered/proxy/tablist/VelocityTabList.java

@@ -16,10 +16,11 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
 import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
 
 public class VelocityTabList implements TabList {
     private final MinecraftConnection connection;
-    private final Map<UUID, TabListEntry> entries = new HashMap<>();
+    private final Map<UUID, TabListEntry> entries = new ConcurrentHashMap<>();
 
     public VelocityTabList(MinecraftConnection connection) {
         this.connection = connection;