Document modification event fired even if document is not updated

Steps to Reproduce

1. Run a PUT request on a document but do not update any properties, ex.

   curl -X PUT 'http://localhost:8080/nuxeo/api/v1/path/<path_to_document>' -H 'Content-type: application/json' -u Administrator:Administrator -d '{"entity-type":"document"}'
   

2. Look at the history tab of the document. Notice that a documentModified event was fired
3. Look at the dc:modified date of the document. Notice that it is not updated

Expected Results: Document modification event should be fired when document is actually modified