Paper/nms-patches/CommandTeleport.patch

--- a/net/minecraft/server/CommandTeleport.java
+++ b/net/minecraft/server/CommandTeleport.java
@@ -12,6 +12,11 @@
 import java.util.Iterator;
 import java.util.Set;
 import javax.annotation.Nullable;
+// CraftBukkit start
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.CraftWorld;
+import org.bukkit.event.entity.EntityTeleportEvent;
+// CraftBukkit end
 
 public class CommandTeleport {
 
@@ -118,9 +123,9 @@
             }
 
             if (worldserver == entity.world) {
-                ((EntityPlayer) entity).playerConnection.a(d0, d1, d2, f, f1, set);
+                ((EntityPlayer) entity).playerConnection.a(d0, d1, d2, f, f1, set, org.bukkit.event.player.PlayerTeleportEvent.TeleportCause.COMMAND); // CraftBukkit
             } else {
-                ((EntityPlayer) entity).a(worldserver, d0, d1, d2, f, f1);
+                ((EntityPlayer) entity).a(worldserver, d0, d1, d2, f, f1, org.bukkit.event.player.PlayerTeleportEvent.TeleportCause.COMMAND); // CraftBukkit
             }
 
             entity.setHeadRotation(f);
@@ -129,6 +134,21 @@
             float f3 = MathHelper.g(f1);
 
             f3 = MathHelper.a(f3, -90.0F, 90.0F);
+            // CraftBukkit start - Teleport event
+            Location to = new Location(worldserver.getWorld(), d0, d1, d2, f2, f3);
+            EntityTeleportEvent event = new EntityTeleportEvent(entity.getBukkitEntity(), entity.getBukkitEntity().getLocation(), to);
+            worldserver.getServer().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();
+            // CraftBukkit end
             if (worldserver == entity.world) {
                 entity.setPositionRotation(d0, d1, d2, f2, f3);
                 entity.setHeadRotation(f2);