Refactor cmab parsing logic to simplify null check in JsonConfigParser

Author: FarhanAnjum-opti

core-api/src/main/java/com/optimizely/ab/config/parser/JsonConfigParser.java

@@ -176,9 +176,7 @@ private List<Experiment> parseExperiments(JSONArray experimentJson, String group
             Cmab cmab = null;
             if (experimentObject.has("cmab")) {
                 JSONObject cmabObject = experimentObject.optJSONObject("cmab");
-                if (cmabObject != null) {
-                    cmab = parseCmab(cmabObject);
-                }
+                cmab = parseCmab(cmabObject);
             }
 
             experiments.add(new Experiment(id, key, status, layerId, audienceIds, conditions, variations, userIdToVariationKeyMap,