Create list-node elements (part3): NCMP REST and service layers

Issue-ID: CPS-360
Change-Id: Id8be89f19750d72bae334491aea4a59f21c7ecd6
Signed-off-by: Ruslan Kashapov <ruslan.kashapov@pantheon.tech>
diff --git a/cps-ncmp-rest/docs/openapi/components.yaml b/cps-ncmp-rest/docs/openapi/components.yaml
index 69c37ad..5ff3099 100644
--- a/cps-ncmp-rest/docs/openapi/components.yaml
+++ b/cps-ncmp-rest/docs/openapi/components.yaml
@@ -1,5 +1,6 @@
 #  ============LICENSE_START=======================================================
 #  Modification (C) 2021 Nordix Foundation
+#  Modifications Copyright (C) 2021 Pantheon.tech
 #  ================================================================================
 #  Licensed under the Apache License, Version 2.0 (the "License");
 #  you may not use this file except in compliance with the License.
@@ -52,6 +53,13 @@
       schema:
         type: string
         default: /
+    requiredXpathInQuery:
+      name: xpath
+      in: query
+      description: xpath
+      required: true
+      schema:
+        type: string
     includeDescendantsOptionInQuery:
       name: include-descendants
       in: query