Set a default time zone for Elasticsearch date histogram

Dates are stored internally as UTC inside Elasticsearch.

Nuxeo is sending date with the time zone information so there is nothing to do explicitly for indexing and searching.

But for date histogram we submit an interval and date are returned as UTC because Elasticsearch don't know our time zone.

This can be fixed by using the timeZone aggregate option.

We might set this option by default to the platform time zone ?