SOL003 VNF Performance Management - Implementation of deltas between v3.3.1 and v2.7.1

This merge request refers to the implementation of deltas between v3.3.1 and v2.7.1 of SOL003 VNF Performance Management Interface.

@lynchpi @aelken @matsuurat @carignani @sayama @kraja @zulfiqar @zafar

Deadline for review: Friday 12th March 2021 @6pm CET

Review period elapsed: approved !

SOL003/VNFPerformanceManagement-API/environment/variables.txt

@@ -9,6 +9,7 @@ ${AUTHORIZATION_TOKEN}    Bearer 0b79bab50daca910b000d4f1a2b675d604257e42
 ${NEG_AUTHORIZATION}    Bearer negativetoken
 
 ${CONTENT_TYPE_JSON}    application/json
+${CONTENT_TYPE_PATCH}    application/merge-patch+json
 ${ACCEPT_JSON}    application/json
 ${AUTH_USAGE}     1
 ${FIELD_USAGE}    1
@@ -22,6 +23,7 @@ ${apiName}        vnfpm
 
 ${callback_port}    9091
 ${callback_uri}    http://172.22.1.7:${callback_port}
+${unreachable_callback_uri}    http://not-reachable-uri
 ${callback_endpoint}    /vnfpm/subscriptions
 ${callback_endpoint_error}    /subs_404
 ${sleep_interval}    20s