Update schema to get rid of nullable which isn't valid 3.1.

Signed-off-by: Aramis Sennyey <sennyeya@amazon.com>

plugins/catalog-backend/openapi.yaml

@@ -257,7 +257,7 @@ components:
           items:
             allOf:
               - $ref: '#/components/schemas/Entity'
-            nullable: true
+              - type: 'null'
           description: |-
             The list of entities, in the same order as the refs in the request. Entries
             that are null signify that no entity existed with that ref.
@@ -455,8 +455,9 @@ components:
             field empty; which would currently make it owned by X" where X is taken from the
             codeowners file.
         value:
-          type: string
-          nullable: true
+          type:
+            - string
+            - 'null'
         state:
           type: string
           enum:

plugins/catalog-backend/schema/openapi.ts

@@ -306,12 +306,14 @@ export default {
           items: {
             type: 'array',
             items: {
-              allOf: [
+              anyOf: [
                 {
                   $ref: '#/components/schemas/Entity',
                 },
+                {
+                  type: 'null',
+                },
               ],
-              nullable: true,
             },
             description:
               'The list of entities, in the same order as the refs in the request. Entries\nthat are null signify that no entity existed with that ref.',