PaperMC/paper-server/patches/sources/net/minecraft/world/item/SpawnEggItem.java.patch

--- a/net/minecraft/world/item/SpawnEggItem.java
+++ b/net/minecraft/world/item/SpawnEggItem.java
@@ -176,10 +176,10 @@
                     return Optional.empty();
                 } else {
                     ((Mob) object).moveTo(pos.x(), pos.y(), pos.z(), 0.0F, 0.0F);
-                    world.addFreshEntityWithPassengers((Entity) object);
+                    world.addFreshEntityWithPassengers((Entity) object, org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.SPAWNER_EGG); // CraftBukkit
                     ((Mob) object).setCustomName((Component) stack.get(DataComponents.CUSTOM_NAME));
                     stack.consume(1, user);
-                    return Optional.of(object);
+                    return Optional.of((Mob) object); // CraftBukkit - decompile error
                 }
             }
         }