./events api should raise an error if the database session cannot be opened

Current Situation

• The ./events api is called by JOC to know when a site should be updated.
• Whenever this web service responses with HTTP code 200 then it is called immediately again for next events.
• If this web service cannot open a database session then it doesn't send an error message.
  It sends {"events":[]} with HTTP code 200 again and again in rapid repetition and logs only

  No valid session factory available. Can not open hibernate session.

Desired Behavior

• ./events api should send a HTTP code 420 with error message if the database session cannot be opened.

Workaround

A patch is provided for JOC Cockpit 1.12.7
See the description how to apply a patch in JOC