Missing callback in createS3EventSource when notification configuration already exists

[taoweng100]

common.js/createS3EventSource method:
There is a missing callback in case of notification configuration already exists.

At line 574 of common.js
Could you please change the code from:

if (!configAlreadyExists){
logger.info('Creating notification configuration');

to:

if (configAlreadyExists) {
callback();
} else {
logger.info('Creating notification configuration');