Upstream

Essentials/src/main/java/com/earth2me/essentials/Essentials.java

@@ -86,6 +86,7 @@
 import net.ess3.provider.providers.ModernPlayerLocaleProvider;
 import net.ess3.provider.providers.ModernPotionMetaProvider;
 import net.ess3.provider.providers.ModernSignDataProvider;
+import net.ess3.provider.providers.ModernSyncCommandsProvider;
 import net.ess3.provider.providers.PaperBiomeKeyProvider;
 import net.ess3.provider.providers.PaperContainerProvider;
 import net.ess3.provider.providers.PaperKnownCommandsProvider;
@@ -393,7 +394,7 @@ public void onEnable() {
             providerFactory.registerProvider(BukkitMaterialTagProvider.class, PaperMaterialTagProvider.class);
 
             // Sync Commands Provider
-            providerFactory.registerProvider(ReflSyncCommandsProvider.class);
+            providerFactory.registerProvider(ReflSyncCommandsProvider.class, ModernSyncCommandsProvider.class);
 
             // Persistent Data Provider
             providerFactory.registerProvider(ReflPersistentDataProvider.class, ModernPersistentDataProvider.class);

Essentials/src/main/java/com/earth2me/essentials/EssentialsPlayerListener.java

@@ -595,8 +595,12 @@ public void onPlayerTeleport(final PlayerTeleportEvent event) {
         if (tickCountProvider != null && ess.getSettings().isWorldChangePreserveFlying() && VersionUtil.getServerBukkitVersion().isHigherThanOrEqualTo(VersionUtil.v1_17_R01)) {
             if (user.isAuthorized("essentials.fly")) {
                 //noinspection DataFlowIssue - not real
-                if (event.getFrom().getWorld() != event.getTo().getWorld() && player.isFlying()) {
-                    user.setFlightTick(tickCountProvider.getTickCount());
+                if (event.getFrom().getWorld() != event.getTo().getWorld() && player.getAllowFlight()) {
+                    // If the player is not flying but has the ability to fly, we set the sign of the tick count to -1
+                    // Later on in the PlayerChangedWorldEvent, we will set the player's flying state to true if the tick count is positive.
+                    // If the tick count is negative, we simply just set the player's flight ability to true.
+                    final int tick = player.isFlying() ? tickCountProvider.getTickCount() : -tickCountProvider.getTickCount();
+                    user.setFlightTick(tick);
                 }
             }
         }
@@ -778,9 +782,12 @@ public void onPlayerChangedWorldFlyReset(final PlayerChangedWorldEvent event) {
         }
 
         final TickCountProvider tickCountProvider = ess.provider(TickCountProvider.class);
-        if (tickCountProvider != null && user.getFlightTick() == tickCountProvider.getTickCount() && user.isAuthorized("essentials.fly")) {
+        final int flightTick = user.getFlightTick();
+        if (tickCountProvider != null && Math.abs(flightTick) == tickCountProvider.getTickCount() && user.isAuthorized("essentials.fly")) {
             user.getBase().setAllowFlight(true);
-            user.getBase().setFlying(true);
+            if (flightTick > 0) {
+                user.getBase().setFlying(true);
+            }
         }
         user.setFlightTick(-1);
     }

providers/BaseProviders/src/main/java/net/ess3/provider/providers/BukkitSpawnerBlockProvider.java

@@ -20,7 +20,7 @@ public void setMinSpawnDelay(final CreatureSpawner spawner, final int delay) {
     @ProviderTest
     public static boolean test() {
         try {
-            CreatureSpawner.class.getDeclaredMethod("setMaxSpawnDelay", int.class);
+            CreatureSpawner.class.getMethod("setMaxSpawnDelay", int.class);
             return true;
         } catch (final NoSuchMethodException ignored) {
             return false;

providers/BaseProviders/src/main/java/net/ess3/provider/providers/ModernSyncCommandsProvider.java

@@ -0,0 +1,28 @@
+package net.ess3.provider.providers;
+
+import net.ess3.provider.SyncCommandsProvider;
+import net.essentialsx.providers.ProviderData;
+import net.essentialsx.providers.ProviderTest;
+import org.bukkit.Bukkit;
+import org.bukkit.entity.Player;
+
+@ProviderData(description = "1.21.4+ Sync Commands Provider", weight = 1)
+public class ModernSyncCommandsProvider implements SyncCommandsProvider {
+    @Override
+    public void syncCommands() {
+        for (final Player player : Bukkit.getOnlinePlayers()) {
+            player.updateCommands();
+        }
+    }
+
+    @ProviderTest
+    public static boolean test() {
+        try {
+            // There isn't a real good way to test this, but we can check if the Creaking class exists.
+            Class.forName("org.bukkit.entity.Creaking");
+            return true;
+        } catch (final Throwable ignored) {
+            return false;
+        }
+    }
+}