PaymentRequestUnion, IssueBillingKeyAndPayRequestUnion optional로 변경

Author: CirnoV

src/schema/browser-sdk.yml

@@ -4561,6 +4561,7 @@ resources:
     IssueBillingKeyAndPayRequestUnion:
       type: discriminatedUnion
       discriminator: billingKeyAndPayMethod
+      optional: true
       types:
         MOBILE:
           type: resourceRef
@@ -4718,6 +4719,7 @@ resources:
     PaymentRequestUnion:
       type: discriminatedUnion
       discriminator: payMethod
+      optional: true
       types:
         CARD:
           type: resourceRef