add test api.yaml

api.yaml

+openapi: 3.0.3
+info:
+  title: Aina
+  description: Aina
+  version: 1.0.0
+servers:
+  - url: 'http://localhost:8080'
+
+paths:
+  /classifier:
+    get:
+      operationId: getClassifier
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/OkayResponse"
+          description: OK
+
+components:
+  schemas:
+    OkayResponse:
+      properties:
+        response:
+          type: string
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