merge
Merges key-values from oldJson and newJson into a new JSONObject. Keys which exist in both oldJson and newJson will be overridden by the values in newJson. Key-values present in oldJson but not newJson will be preserved.
Objects are not copied from their original objects, i.e. mutations of the original json will affect the merged output.
Return
merger of the json objects. Returns a best effort merger of the two JSON objects upon any error.