PaperMC/paper-server/nms-patches/net/minecraft/server/commands/CommandTeleport.patch

--- a/net/minecraft/server/commands/CommandTeleport.java
+++ b/net/minecraft/server/commands/CommandTeleport.java
@@ -33,6 +33,13 @@
 import net.minecraft.world.phys.Vec2F;
 import net.minecraft.world.phys.Vec3D;
 
+// CraftBukkit start
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.CraftWorld;
+import org.bukkit.event.entity.EntityTeleportEvent;
+import org.bukkit.event.player.PlayerTeleportEvent;
+// CraftBukkit end
+
 public class CommandTeleport {
 
     private static final SimpleCommandExceptionType INVALID_POSITION = new SimpleCommandExceptionType(IChatBaseComponent.translatable("commands.teleport.invalidPosition"));
@@ -155,7 +162,30 @@
             float f2 = MathHelper.wrapDegrees(f);
             float f3 = MathHelper.wrapDegrees(f1);
 
-            if (entity.teleportTo(worldserver, d0, d1, d2, set, f2, f3)) {
+            // CraftBukkit start - Teleport event
+            boolean result;
+            if (entity instanceof EntityPlayer player) {
+                result = player.teleportTo(worldserver, d0, d1, d2, set, f2, f3, PlayerTeleportEvent.TeleportCause.COMMAND);
+            } else {
+                Location to = new Location(worldserver.getWorld(), d0, d1, d2, f2, f3);
+                EntityTeleportEvent event = new EntityTeleportEvent(entity.getBukkitEntity(), entity.getBukkitEntity().getLocation(), to);
+                worldserver.getCraftServer().getPluginManager().callEvent(event);
+                if (event.isCancelled()) {
+                    return;
+                }
+
+                d0 = to.getX();
+                d1 = to.getY();
+                d2 = to.getZ();
+                f2 = to.getYaw();
+                f3 = to.getPitch();
+                worldserver = ((CraftWorld) to.getWorld()).getHandle();
+
+                result = entity.teleportTo(worldserver, d0, d1, d2, set, f2, f3);
+            }
+
+            if (result) {
+                // CraftBukkit end
                 if (commandteleport_a != null) {
                     commandteleport_a.perform(commandlistenerwrapper, entity);
                 }