chore: make apis nullable (#7763)

what:

- makes top level attributes of each object an optional field in the http layer where possible

RESOLVES CORE-2229

packages/medusa/src/api/admin/draft-orders/validators.ts

@@ -1,6 +1,6 @@
-import { createFindParams, createSelectParams } from "../../utils/validators"
-import { AddressPayload, BigNumberInput } from "../../utils/common-validators"
 import { z } from "zod"
+import { AddressPayload, BigNumberInput } from "../../utils/common-validators"
+import { createFindParams, createSelectParams } from "../../utils/validators"
 
 export type AdminGetOrderParamsType = z.infer<typeof AdminGetOrderParams>
 export const AdminGetOrderParams = createSelectParams()
@@ -23,8 +23,8 @@ enum Status {
 }
 
 const ShippingMethod = z.object({
-  shipping_method_id: z.string().optional(),
-  order_id: z.string().optional(),
+  shipping_method_id: z.string().nullish(),
+  order_id: z.string().nullish(),
   name: z.string(),
   option_id: z.string(),
   data: z.record(z.string(), z.unknown()).optional(),
@@ -33,13 +33,13 @@ const ShippingMethod = z.object({
 
 const Item = z
   .object({
-    title: z.string().optional(),
-    sku: z.string().optional(),
-    barcode: z.string().optional(),
-    variant_id: z.string().optional(),
-    unit_price: BigNumberInput.optional(),
+    title: z.string().nullish(),
+    sku: z.string().nullish(),
+    barcode: z.string().nullish(),
+    variant_id: z.string().nullish(),
+    unit_price: BigNumberInput.nullish(),
     quantity: z.number(),
-    metadata: z.record(z.string(), z.unknown()).optional(),
+    metadata: z.record(z.unknown()).nullish(),
   })
   .refine((data) => {
     if (!data.variant_id) {
@@ -53,18 +53,18 @@ export type AdminCreateDraftOrderType = z.infer<typeof AdminCreateDraftOrder>
 export const AdminCreateDraftOrder = z
   .object({
     status: z.nativeEnum(Status).optional(),
-    sales_channel_id: z.string().optional(),
-    email: z.string().optional(),
-    customer_id: z.string().optional(),
+    sales_channel_id: z.string().nullish(),
+    email: z.string().nullish(),
+    customer_id: z.string().nullish(),
     billing_address: AddressPayload.optional(),
     shipping_address: AddressPayload.optional(),
     items: z.array(Item).optional(),
     region_id: z.string(),
     promo_codes: z.array(z.string()).optional(),
-    currency_code: z.string().optional(),
+    currency_code: z.string().nullish(),
     no_notification_order: z.boolean().optional(),
     shipping_methods: z.array(ShippingMethod),
-    metadata: z.record(z.string(), z.unknown()).optional(),
+    metadata: z.record(z.unknown()).nullish(),
   })
   .strict()
   .refine(