PaperMC/paper-server/nms-patches/net/minecraft/world/entity/monster/EntityShulker.patch

--- a/net/minecraft/world/entity/monster/EntityShulker.java
+++ b/net/minecraft/world/entity/monster/EntityShulker.java
@@ -60,6 +60,12 @@
 import net.minecraft.world.phys.Vec3D;
 import org.joml.Vector3f;
 
+// CraftBukkit start
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.util.CraftLocation;
+import org.bukkit.event.entity.EntityTeleportEvent;
+// CraftBukkit end
+
 public class EntityShulker extends EntityGolem implements VariantHolder<Optional<EnumColor>>, IMonster {
 
     private static final UUID COVERED_ARMOR_MODIFIER_UUID = UUID.fromString("7E0292F2-9434-48D5-A29F-9583AF7DF27F");
@@ -408,6 +414,16 @@
                     EnumDirection enumdirection = this.findAttachableSurface(blockposition1);
 
                     if (enumdirection != null) {
+                        // CraftBukkit start
+                        EntityTeleportEvent teleport = new EntityTeleportEvent(this.getBukkitEntity(), this.getBukkitEntity().getLocation(), CraftLocation.toBukkit(blockposition1, this.level().getWorld()));
+                        this.level().getCraftServer().getPluginManager().callEvent(teleport);
+                        if (!teleport.isCancelled()) {
+                            Location to = teleport.getTo();
+                            blockposition1 = BlockPosition.containing(to.getX(), to.getY(), to.getZ());
+                        } else {
+                            return false;
+                        }
+                        // CraftBukkit end
                         this.unRide();
                         this.setAttachFace(enumdirection);
                         this.playSound(SoundEffects.SHULKER_TELEPORT, 1.0F, 1.0F);
@@ -478,7 +494,7 @@
                 if (entityshulker != null) {
                     entityshulker.setVariant(this.getVariant());
                     entityshulker.moveTo(vec3d);
-                    this.level().addFreshEntity(entityshulker);
+                    this.level().addFreshEntity(entityshulker, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.BREEDING); // CraftBukkit - the mysteries of life
                 }
 
             }