disallow two or more querystrings

Author: karenetheridge

src/schemas/validation/schema.yaml

@@ -314,6 +314,16 @@ $defs:
                     const: querystring
                 required:
                   - in
+        contains:
+          type: object
+          properties:
+            in:
+              const: querystring
+          required:
+            - in
+        minContains: 0
+        maxContains: 1
+
       requestBody:
         $ref: '#/$defs/request-body-or-reference'
       responses:

tests/schema/fail/parameter-object-two-querystrings.yaml

@@ -0,0 +1,20 @@
+openapi: 3.2.0
+info:
+  title: API
+  version: 1.0.0
+components:
+  pathItems:
+    my-path-item:
+      get:
+        description: querystring cannot be used twice
+        parameters:
+          - name: myquerystring1
+            in: querystring
+            content:
+              application/json:
+                schema: {}
+          - name: myquerystring2
+            in: querystring
+            content:
+              application/json:
+                schema: {}