[moveos_std] Missing event when display object create

[YusongWang]

In the library, when the users issue new collections, they will create a display object when the contract init.

The indexer needs a mark to know the object is to the display type.

    #[private_generics(T)]
    /// Create or borrow_mut Display object for resource `T`
    /// Only the module of `T` can call this function.
    public fun resource_display<T: key>(): &mut Object<Display<T>> {
        let object_id = object::named_object_id<Display<T>>();
        if (!object::exists_object(object_id)) {
            let display_obj = object::new_named_object(Display<T> {
                sample_map: simple_map::create()
            });
            //We transfer the display object to the moveos_std
            //And the caller do not need to care about the display object
            object::transfer_extend(display_obj, @moveos_std);
        };
        object::borrow_mut_object_extend<Display<T>>(object_id)
    }

    #[private_generics(T)]
    /// Create or borrow_mut Display object for `Object<T>`
    /// Only the module of `T` can call this function.
    public fun object_display<T: key>(): &mut Object<Display<Object<T>>> {
        let object_id = object::named_object_id<Display<Object<T>>>();
        if (!object::exists_object(object_id)) {
            let display_obj = object::new_named_object(Display<Object<T>> {
                sample_map: simple_map::create()
            });
            //We transfer the display object to the moveos_std
            //And the caller do not need to care about the display object
            object::transfer_extend(display_obj, @moveos_std);
        };
        object::borrow_mut_object_extend<Display<Object<T>>>(object_id)
    }

The solution is here

    #[private_generics(T)]
    /// Create or borrow_mut Display object for resource `T`
    /// Only the module of `T` can call this function.
    public fun resource_display<T: key>(): &mut Object<Display<T>> {
        let object_id = object::named_object_id<Display<T>>();
        if (!object::exists_object(object_id)) {
            let display_obj = object::new_named_object(Display<T> {
                sample_map: simple_map::create()
            });
            //We transfer the display object to the moveos_std
            //And the caller do not need to care about the display object
            object::transfer_extend(display_obj, @moveos_std);
        };

      //emit display create event
      emit display_create<Display<T>>();

        object::borrow_mut_object_extend<Display<T>>(object_id)
    }

    #[private_generics(T)]
    /// Create or borrow_mut Display object for `Object<T>`
    /// Only the module of `T` can call this function.
    public fun object_display<T: key>(): &mut Object<Display<Object<T>>> {
        let object_id = object::named_object_id<Display<Object<T>>>();
        if (!object::exists_object(object_id)) {
            let display_obj = object::new_named_object(Display<Object<T>> {
                sample_map: simple_map::create()
            });
            //We transfer the display object to the moveos_std
            //And the caller do not need to care about the display object
            object::transfer_extend(display_obj, @moveos_std);
        };

        // emit display create event
        emit display_create<Display<T>>();

        object::borrow_mut_object_extend<Display<Object<T>>>(object_id)
    }

Is nothing todo with the event . just claim the new display resoures has been create