feat(events): Add Gate generated id in the event being sent to echo

Set the Gate generated event id as the top level event id in the event being sent to Echo.
This conforms to Event.java as used by Echo to deserialize the event upon receipt.
This also prevents Echo from generating yet another UUID.

gate-web/src/main/groovy/com/netflix/spinnaker/gate/services/PipelineService.groovy

@@ -97,6 +97,9 @@ class PipelineService {
     parameters.put("eventId", eventId)
     parameters.put("executionId", executionId)
 
+    // Note that the Gate generated UUID is used as the event id and set it at the top level of the Map.
+    // This conforms to Event.java as used by Echo to deserialize the event upon receipt.
+    // This also prevents Echo from generating yet another UUID.
     Map eventMap = [
       content: [
         application     : application,
@@ -106,7 +109,8 @@ class PipelineService {
       ],
       details: [
         type: "manual"
-      ]
+      ],
+      eventId: eventId
     ]
     echoService.postEvent(eventMap)
     return [