title: s3api put-bucket-notification-configuration deletes existing events
body: <p>I am trying to add Event Notification in s3 bucket using put-bucking-notification API. It is overwriting the existing event notification with the newly submitted event. What I want to achieve is to add a new event notification to the existing list of events.</p>
  
  <p>I am able to do that from amazon console. I found that amazon is using an undocumented API PutAllBucketNotification to implement this.</p>
  
  <p>Is it possible to do the same using boto3/java ?</p>