Use rules.payload when extracting data for event stream (#4607)

* Use rules.payload when extracting data for event stream

* chore: npm run add-change

---------

Co-authored-by: Kamat, Trivikram <[email protected]>

Author: inf3rnus

Diff for: .changes/next-release/bugfix-rest-json-7a3f1db2.json

@@ -0,0 +1,5 @@
+{
+  "type": "bugfix",
+  "category": "rest-json",
+  "description": "use rules.payload when extracting data for event stream"
+}

Diff for: lib/protocol/rest_json.js

@@ -1,3 +1,4 @@
+var AWS = require('../core');
 var util = require('../util');
 var Rest = require('./rest');
 var Json = require('./json');
@@ -75,7 +76,7 @@ function extractData(resp) {
     var body = resp.httpResponse.body;
     if (payloadMember.isEventStream) {
       parser = new JsonParser();
-      resp.data[payload] = util.createEventStream(
+      resp.data[rules.payload] = util.createEventStream(
         AWS.HttpClient.streamsApiVersion === 2 ? resp.httpResponse.stream : body,
         parser,
         payloadMember