implemented possible player teleportation invisibility fix. enable it in config.yml, at "settings.fix-invisible-after-tp", ONLY IF NEEDED. only some buggy Spigot versions have this issue.

.gitignore

@@ -1 +1,2 @@
 .idea/
+out/

ant_buildversion_end.txt

@@ -1 +1 @@
-Changing back build version 10.0.161 in file plugin.yml to BUILD_VERSION...
+Changing back build version 10.0.165 in file plugin.yml to BUILD_VERSION...

build.number

@@ -1,5 +1,5 @@
 #Build Number for ANT. Do not edit!
-#Sat Apr 04 18:08:45 CEST 2020
-build.number=162
+#Fri Jun 12 13:50:42 CEST 2020
+build.number=166
 \#Build=Number for ANT. Do not edit\!
 \#Tue=Jul 30 16\:09\:09 CEST 2019

src/config.yml

@@ -16,4 +16,5 @@ teleportation:
   teleport-to-hub-on-respawn: false
   respawn-handler: true
 settings:
-  multiverse-bypass: false
+  multiverse-bypass: false
+  fix-invisible-after-tp: false

src/net/mindoverflow/hubthat/commands/WorldTpCommand.java

@@ -12,6 +12,9 @@ import org.bukkit.entity.Player;
 
 import java.util.logging.Level;
 
+import static net.mindoverflow.hubthat.utils.TeleportUtils.fixInvisibilityAfter;
+import static net.mindoverflow.hubthat.utils.TeleportUtils.fixInvisibilityBefore;
+
 public class WorldTpCommand implements CommandExecutor
 {
 
@@ -70,7 +73,9 @@ public class WorldTpCommand implements CommandExecutor
             // Cast Player to commandSender so we can teleport it.
             Player player = (Player)commandSender;
             // Teleport the Player.
-            player.teleport(destinationLocation);
+            fixInvisibilityBefore(player, destinationLocation);
+            plugin.getServer().getScheduler().runTaskLater(plugin, () -> player.teleport(destinationLocation), 1);
+            fixInvisibilityAfter(player);
             // Tell the player he has been teleported.
             String teleportedMessage = MessageUtils.getLocalizedMessage(LocalizedMessages.INFO_WORLDTP_TELEPORTED, false);
             teleportedMessage = teleportedMessage.replace("%world%", destinationWorldName).replace("%w%", destinationWorldName);

src/net/mindoverflow/hubthat/utils/CommonValues.java

@@ -1,5 +1,8 @@
 package net.mindoverflow.hubthat.utils;
 
+import org.bukkit.Material;
+import org.bukkit.inventory.ItemStack;
+
 import java.util.ArrayList;
 
 public class CommonValues
@@ -10,4 +13,6 @@ public class CommonValues
     public static ArrayList<String>cancelRunnable = new ArrayList<>();
 
     public static Boolean updateChecker = true;
+    public static boolean invisibilityFix = false; // sometimes, in buggy versions of Spigot, players become invisible after getting teleported. this fixes the problem.
+    public static final ItemStack AIR = new ItemStack(Material.AIR, 1);
 }

src/net/mindoverflow/hubthat/utils/ConfigEntries.java

@@ -24,6 +24,8 @@ public enum ConfigEntries
 
     MULTIVERSE_BYPASS("settings.multiverse-bypass"),
 
+    INVISIBILITY_FIX("settings.fix-invisible-after-tp"),
+
     //UPDATE_CHECKER_ENABLE("updates.enable-update-checker"),
     ;
 

src/net/mindoverflow/hubthat/utils/Debugger.java

@@ -10,7 +10,7 @@ import java.util.logging.Level;
 public class Debugger
 {
     // Enable or disable debugging messages (aka verbosity).
-    private final boolean DEBUGGING = false;
+    private final boolean DEBUGGING = true;
 
     // Initialize needed variables. We will need those variables to be able to precisely debug the plugin.
     private String className;

src/net/mindoverflow/hubthat/utils/TeleportUtils.java

@@ -24,7 +24,11 @@ public class TeleportUtils
     {
         Location location = new Location(plugin.getServer().getWorld(worldName), x, y, z, (float)yaw, (float)pitch);
         Player player = plugin.getServer().getPlayer(playerName);
-        player.teleport(location);
+        if(player == null) return;
+
+        fixInvisibilityBefore(player, location);
+        plugin.getServer().getScheduler().runTaskLater(plugin, () -> player.teleport(location), 1);
+        fixInvisibilityAfter(player);
     }
 
     // Method to teleport a player, given its username and defined if it's a hub or a spawn.
@@ -121,7 +125,9 @@ public class TeleportUtils
 
         // Store the location in a variable and teleport the player to it.
         final Location finalLocation = new Location(destinationWorld, x, y, z, (float)yaw, (float)pitch);
-        player.teleport(finalLocation);
+        fixInvisibilityBefore(player, finalLocation);
+        plugin.getServer().getScheduler().runTaskLater(plugin, () -> player.teleport(finalLocation), 1);
+        fixInvisibilityAfter(player);
 
         // Check if the player is teleporting to the hub.
         if(type == FileUtils.FileType.HUB_YAML)
@@ -135,7 +141,7 @@ public class TeleportUtils
                 sender.sendMessage(message);
             }
         }
-        else if(type == FileUtils.FileType.SPAWN_YAML)
+        else //if(type == FileUtils.FileType.SPAWN_YAML) // left here but commented, for easy understanding
         {
             MessageUtils.sendLocalizedMessage(player, LocalizedMessages.INFO_SPAWN_TELEPORTED);
 
@@ -150,4 +156,19 @@ public class TeleportUtils
     {
         teleportPlayer(sender, player, type, null);
     }
+
+    public static void fixInvisibilityAfter(Player player)
+    {
+        if(CommonValues.invisibilityFix)
+        {
+            debugger.sendDebugMessage(Level.INFO, "Invisibility fix enabled!");
+            player.getInventory().addItem(CommonValues.AIR);
+        }
+    }
+
+    public static void fixInvisibilityBefore(Player player, Location destination)
+    {
+        destination.getChunk().load();
+    }
+
 }

src/net/mindoverflow/hubthat/utils/files/FileUtils.java

@@ -70,6 +70,7 @@ public class FileUtils
             UpdateChecker.task = plugin.getServer().getScheduler().runTaskTimerAsynchronously(plugin, plugin.updateChecker, 1, 20 * 60 * 60 * 12);
         }
 
+        CommonValues.invisibilityFix = config.getBoolean(ConfigEntries.INVISIBILITY_FIX.path);
     }
 
     // Only reload the needed File.