Fix issue where old player objects were not cleaned up properly.

This is caused by an issue with the event order in Spigot (and Spigot derivatives), so the fix is rather hacky.

Bukkit/src/main/java/com/plotsquared/bukkit/BukkitMain.java

@@ -392,6 +392,19 @@ public final class BukkitMain extends JavaPlugin implements Listener, IPlotMain<
         PlotSquared.log(
             Captions.PREFIX.getTranslated() + "Using platform world manager: " + this.worldManager
                 .getName());
+
+        // Clean up potential memory leak
+        Bukkit.getScheduler().runTaskTimer(this, () -> {
+            try {
+                for (final PlotPlayer<? extends Player> player : this.getPlayerManager().getPlayers()) {
+                    if (player.getPlatformPlayer() == null || !player.getPlatformPlayer().isOnline()) {
+                        this.getPlayerManager().removePlayer(player);
+                    }
+                }
+            } catch (final Exception e) {
+                getLogger().warning("Failed to clean up players: " + e.getMessage());
+            }
+        }, 100L, 100L);
     }
 
     private void unload() {
@@ -982,7 +995,7 @@ public final class BukkitMain extends JavaPlugin implements Listener, IPlotMain<
     }
 
     @Override public void unregister(@NonNull final PlotPlayer player) {
-        BukkitUtil.removePlayer(player.getName());
+        BukkitUtil.removePlayer(player.getUUID());
     }
 
     @Override public void registerChunkProcessor() {

Bukkit/src/main/java/com/plotsquared/bukkit/listener/PlayerEvents.java

@@ -650,10 +650,10 @@ public class PlayerEvents extends PlotListener implements Listener {
         PlotSquared.get().getImpromptuUUIDPipeline().storeImmediately(event.getName(), uuid);
     }
 
-    @EventHandler(priority = EventPriority.LOWEST, ignoreCancelled = true)
+    @EventHandler(priority = EventPriority.HIGHEST, ignoreCancelled = true)
     public void onConnect(PlayerJoinEvent event) {
         final Player player = event.getPlayer();
-        BukkitUtil.removePlayer(player.getName());
+        BukkitUtil.removePlayer(player.getUniqueId());
         final PlotPlayer<Player> pp = BukkitUtil.getPlayer(player);
 
         Location location = pp.getLocation();

Bukkit/src/main/java/com/plotsquared/bukkit/util/BukkitUtil.java

@@ -116,9 +116,11 @@ public class BukkitUtil extends WorldUtil {
     private static Player lastPlayer = null;
     private static BukkitPlayer lastPlotPlayer = null;
 
-    public static void removePlayer(String player) {
+    public static void removePlayer(UUID uuid) {
         lastPlayer = null;
         lastPlotPlayer = null;
+        // Make sure that it's removed internally
+        PlotSquared.imp().getPlayerManager().removePlayer(uuid);
     }
 
     public static PlotPlayer<Player> getPlayer(@NonNull final OfflinePlayer op) {

Core/src/main/java/com/plotsquared/core/plot/Plot.java

@@ -2917,7 +2917,7 @@ public class Plot {
      */
     public void reEnter() {
         TaskManager.runTaskLater(() -> {
-            for (PlotPlayer pp : Plot.this.getPlayersInPlot()) {
+            for (PlotPlayer<?> pp : Plot.this.getPlayersInPlot()) {
                 PlotListener.plotExit(pp, Plot.this);
                 PlotListener.plotEntry(pp, Plot.this);
             }
@@ -2925,18 +2925,19 @@ public class Plot {
     }
 
     public void debug(@NotNull final String message) {
+        try {
             final Collection<PlotPlayer<?>> players = PlotPlayer.getDebugModePlayersInPlot(this);
             if (players.isEmpty()) {
                 return;
             }
-        final String string = Captions.PLOT_DEBUG.getTranslated().replace("%plot%", this.toString())
+            final String string =
-            .replace("%message%", message);
+                Captions.PLOT_DEBUG.getTranslated().replace("%plot%", this.toString()).replace("%message%", message);
             for (final PlotPlayer<?> player : players) {
-            if (isOwner(player.getUUID()) ||
+                if (isOwner(player.getUUID()) || Permissions.hasPermission(player, Captions.PERMISSION_ADMIN_DEBUG_OTHER)) {
-                Permissions.hasPermission(player, Captions.PERMISSION_ADMIN_DEBUG_OTHER)) {
                     player.sendMessage(string);
                 }
             }
+        } catch (final Exception ignored) {}
     }
 
     /**

Core/src/main/java/com/plotsquared/core/util/PlayerManager.java

@@ -30,6 +30,7 @@ import com.plotsquared.core.player.PlotPlayer;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -55,6 +56,17 @@ public abstract class PlayerManager<P extends PlotPlayer<? extends T>, T> {
         }
     }
 
+    /**
+     * Remove a player from the player map
+     *
+     * @param uuid Player to remove
+     */
+    public void removePlayer(@NotNull final UUID uuid) {
+        synchronized (playerLock) {
+            this.playerMap.remove(uuid);
+        }
+    }
+
     /**
      * Get the player from its UUID if it is stored in the player map.
      *
@@ -110,7 +122,7 @@ public abstract class PlayerManager<P extends PlotPlayer<? extends T>, T> {
         }
     }
 
-    @NotNull protected abstract P createPlayer(@NotNull final UUID uuid);
+    @NotNull public abstract P createPlayer(@NotNull final UUID uuid);
 
     /**
      * Get an an offline player object from the player's UUID
@@ -134,7 +146,7 @@ public abstract class PlayerManager<P extends PlotPlayer<? extends T>, T> {
      * @return Unmodifiable collection of players
      */
     public Collection<P> getPlayers() {
-        return Collections.unmodifiableCollection(this.playerMap.values());
+        return Collections.unmodifiableCollection(new ArrayList<>(this.playerMap.values()));
     }