Structured Exception details for DMI

- Introduced DmiErrorMessage in API docs with 502 Bad Gateway
- HttpClientRequestException will be thrown which will be exposed as 502 BAD Gateway for the client from NCMP

Issue-ID: CPS-917
Change-Id: Iba8f159e8216bc1f63a9ab86208e5c802437e2e8
Signed-off-by: mpriyank <priyank.maheshwari@est.tech>
diff --git a/cps-ncmp-rest/docs/openapi/components.yaml b/cps-ncmp-rest/docs/openapi/components.yaml
index 69225ae..092c0a2 100644
--- a/cps-ncmp-rest/docs/openapi/components.yaml
+++ b/cps-ncmp-rest/docs/openapi/components.yaml
@@ -30,7 +30,23 @@
           type: string
         details:
           type: string
-
+    # DMI Server Exception Schema
+    DmiErrorMessage:
+      title: DMI Error Message
+      type: object
+      properties:
+        message:
+          type: string
+          example: "Bad Gateway Error Message NCMP"
+        dmi-response:
+          type: object
+          properties:
+            http-code:
+              type: integer
+              example: 400
+            body:
+              type: string
+              example: Bad Request
     # Request Schemas
     RestDmiPluginRegistration:
       type: object
@@ -434,3 +450,14 @@
             status: 500
             message: Internal Server Error
             details: Internal Server Error occurred
+    BadGateway:
+      description: Bad Gateway
+      content:
+        application/json:
+          schema:
+            $ref: "#/components/schemas/DmiErrorMessage"
+          example:
+            message: "Bad Gateway Error Message NCMP"
+            dmi-response:
+              http-code: 400
+              body: "Bad Request"