adds the 422 example

Author: kevinmason-nhs

sandbox/src/mocks/r4/NHSDigital-OperationOutcome-422.json

@@ -0,0 +1,21 @@
+{
+  "resourceType": "OperationOutcome",
+  "meta": {
+    "lastUpdated": "2022-03-01T10:00:00.42Z"
+  },
+  "issue": [
+    {
+      "severity": "error",
+      "code": "invalid",
+      "details": {
+        "coding": [
+          {
+            "system": "https://fhir.nhs.uk/CodeSystem/http-error-codes",
+            "code": "PENDING"
+          }
+        ]
+      },
+      "diagnostics": "The file is being scanned and cannot be retrieved. Wait at least 5 minutes before checking its availability again."
+    }
+  ]
+}

specification/components/r4/schemas/endpoints/a042-retrieve-attachment.yaml

@@ -101,7 +101,7 @@ responses:
   '404':
     $ref: '../responses/NotFound.yaml'
   '422':
-    $ref: '../responses/NotFound.yaml'
+    $ref: '../responses/retrieveAttachment/422Response.yaml'
   '429':
     $ref: '../responses/TooManyRequests.yaml'
   '500':