Merge pull request #12428 from cyrillefr/RedundantPresenceValidationOnBelongs_part_III

Fix RedundantPresenceValidationOnBelongs on two files

app/models/spree/stock_item.rb

@@ -2,15 +2,12 @@
 
 module Spree
   class StockItem < ApplicationRecord
-    self.belongs_to_required_by_default = false
-
     acts_as_paranoid
 
     belongs_to :stock_location, class_name: 'Spree::StockLocation', inverse_of: :stock_items
     belongs_to :variant, -> { with_deleted }, class_name: 'Spree::Variant'
     has_many :stock_movements, dependent: :destroy
 
-    validates :stock_location, :variant, presence: true
     validates :variant_id, uniqueness: { scope: [:stock_location_id, :deleted_at] }
     validates :count_on_hand, numericality: { greater_than_or_equal_to: 0, unless: :backorderable? }
 

app/models/spree/stock_movement.rb

@@ -2,14 +2,11 @@
 
 module Spree
   class StockMovement < ApplicationRecord
-    self.belongs_to_required_by_default = false
-
     belongs_to :stock_item, class_name: 'Spree::StockItem'
-    belongs_to :originator, polymorphic: true
+    belongs_to :originator, polymorphic: true, optional: true
 
     after_create :update_stock_item_quantity
 
-    validates :stock_item, presence: true
     validates :quantity, presence: true
 
     scope :recent, -> { order('created_at DESC') }