PaperMC/nms-patches/EntityShulker.patch

--- a/net/minecraft/server/EntityShulker.java
+++ b/net/minecraft/server/EntityShulker.java
@@ -6,6 +6,10 @@
 import java.util.UUID;
 import java.util.function.Predicate;
 import javax.annotation.Nullable;
+// CraftBukkit start
+import org.bukkit.Location;
+import org.bukkit.event.entity.EntityTeleportEvent;
+// CraftBukkit end
 
 public class EntityShulker extends EntityGolem implements IMonster {
 
@@ -326,8 +330,17 @@
                         EnumDirection enumdirection = aenumdirection[k];
 
                         if (this.world.q(blockposition1.shift(enumdirection))) {
-                            this.datawatcher.set(EntityShulker.a, enumdirection);
-                            flag = true;
+                            // CraftBukkit start
+                            EntityTeleportEvent teleport = new EntityTeleportEvent(this.getBukkitEntity(), this.getBukkitEntity().getLocation(), new Location(this.world.getWorld(), blockposition1.getX(), blockposition1.getY(), blockposition1.getZ()));
+                            this.world.getServer().getPluginManager().callEvent(teleport);
+                            if (!teleport.isCancelled()) {
+                                Location to = teleport.getTo();
+                                blockposition1 = new BlockPosition(to.getX(), to.getY(), to.getZ());
+
+                                this.datawatcher.set(EntityShulker.a, enumdirection);
+                                flag = true;
+                            }
+                            // CraftBukkit end
                             break;
                         }
                     }