Shopify note_attributes not saving

create1.rb

order = ShopifyAPI::Order.new
order.line_items = [{
  :quantity => 1,
  :product_id => 222,
  :variant_id => 333
}]

# as a JSON object
order.note_attributes = [{:foo => 'bar'}]

order.save!

order.reload
puts order.note_attributes.inspect
# => []

create2.rb

order = ShopifyAPI::Order.new
order.line_items = [{
  :quantity => 1,
  :product_id => 222,
  :variant_id => 333
}]

# as a stringified JSON object, per the documentation
# http://docs.shopify.com/api/order
order.note_attributes = [{:foo => 'bar'}].to_json

order.save!

order.reload
puts order.note_attributes.inspect
# => []

update1.rb

order = ShopifyAPI::Order.new
order.line_items = [{
  :quantity => 1,
  :product_id => 222,
  :variant_id => 333
}]
order.save!

# as a JSON object
order.note_attributes = [{:foo => 'bar'}]
order.save!

order.reload
puts order.note_attributes.inspect
# => []

update2.rb

order = ShopifyAPI::Order.new
order.line_items = [{
  :quantity => 1,
  :product_id => 222,
  :variant_id => 333
}]
order.save!

# as a stringified JSON object, per the documentation
# http://docs.shopify.com/api/order
order.note_attributes = [{:foo => 'bar'}].to_json
order.save!

order.reload
puts order.note_attributes.inspect
# => []

update2_put.json

{
	"order": {
		"line_items": [{
			"fulfillment_service": "manual",
			"fulfillment_status": null,
			"grams": 0,
			"id": 111,
			"price": "0.00",
			"product_id": 222,
			"quantity": 1,
			"requires_shipping": true,
			"sku": null,
			"taxable": true,
			"title": "Placeholder Product",
			"variant_id": 333,
			"variant_title": null,
			"vendor": null,
			"name": "Placeholder Product",
			"variant_inventory_management": null,
			"properties": [],
			"product_exists": true,
			"tax_lines": []
		}],
		"id": 444,
		"buyer_accepts_marketing": false,
		"cancel_reason": null,
		"cancelled_at": null,
		"cart_token": null,
		"checkout_token": null,
		"closed_at": null,
		"confirmed": true,
		"created_at": "2014-04-13T14:30:00-04:00",
		"currency": "USD",
		"email": "",
		"financial_status": "paid",
		"fulfillment_status": null,
		"gateway": "",
		"landing_site": null,
		"location_id": null,
		"name": "#1032",
		"note": null,
		"number": 32,
		"reference": null,
		"referring_site": null,
		"source": "api",
		"source_identifier": null,
		"source_name": "api",
		"source_url": null,
		"subtotal_price": "0.00",
		"taxes_included": false,
		"test": false,
		"token": "...",
		"total_discounts": "0.00",
		"total_line_items_price": "0.00",
		"total_price": "0.00",
		"total_price_usd": "0.00",
		"total_tax": "0.00",
		"total_weight": 0,
		"updated_at": "2014-04-13T14:30:00-04:00",
		"user_id": null,
		"browser_ip": null,
		"landing_site_ref": null,
		"order_number": 1032,
		"discount_codes": [],
		"note_attributes": "[{\"foo\":\"bar\"}]",
		"processing_method": "",
		"checkout_id": null,
		"tax_lines": [],
		"tags": "",
		"shipping_lines": [],
		"fulfillments": []
	}
}