Update API definitions

Author: rebilly-machine-user

openapi/components/schemas/RecurringOrder.yaml

@@ -208,9 +208,13 @@ properties:
       Date and time when the subscription starts.
       If this value is `null`, the current time is used.
       This value cannot be more than one service period in the past.
-    type: string
+    type:
+      - 'string'
+      - 'null'
     x-sortable: true
     x-basic: true
+    example: null
+    default: null
     format: date-time
   activationTime:
     description: Date and time when the order is activated.

openapi/components/schemas/StorefrontSubscription.yaml

@@ -222,6 +222,7 @@ properties:
     x-sortable: true
     x-basic: true
     example: null
+    default: null
     format: date-time
   churnTime:
     description: Date and time when the subscription is deactivated.

openapi/components/schemas/Subscription.yaml

@@ -152,6 +152,7 @@ properties:
     x-sortable: true
     x-basic: true
     example: null
+    default: null
     format: date-time
   churnTime:
     description: Date and time when the subscription is deactivated.