new test case added for SOL003 LCM Subscrption

SOL003/VNFLifecycleManagement-API/Subscriptions.robot

@@ -200,4 +200,17 @@ GET subscriptions - Bad Request Response too Big
     ...    Post-Conditions: none 
     Get subscriptions
     Check HTTP Response Status Code Is    400
-    Check HTTP Response Body Json Schema Is    ProblemDetails
\ No newline at end of file
+    Check HTTP Response Body Json Schema Is    ProblemDetails
+    
+POST Create a new Subscription - Unprocessable Entity
+    [Documentation]    Test ID: 7.3.1.17.16
+    ...    Test title: POST Create a new Subscription - Unprocessable Entity
+    ...    Test objective: The objective is to test that content type of the payload body is supported and the payload body of a request contains syntactically correct data but the data cannot be processed.
+    ...    re-conditions: none
+    ...    Reference: Clause 8.4.5.3.1 - ETSI GS NFV-SOL 002 [2] v2.6.1
+    ...    Config ID: Config_prod_VNFM
+    ...    Applicability: none
+    ...    Post-Conditions: none
+    Post Create subscription
+    Check HTTP Response Status Code Is    422
+    Check HTTP Response Body Json Schema Is  ProblemDetails
\ No newline at end of file