Remove jest API which depends on Elasticsearch native API (also
removed), so no longer depend on lucene for this scope. Replace such
removed dependencies with the Elasticsearch low-level API, which does
not depend on Lucene. That now used API is a REST client with minimal
dependencies, indeed. -As opposed to Elastic's current high-level API,
which still depends on lucene and other Gerrit-constraining libraries.
Do so in order to decouple the elasticsearch client from lucene in
Gerrit. That REST client does not logically require Lucene anyway. Most
importantly, such decoupling now enables upcoming support for more than
just one Elasticsearch server version. This includes the new possibility
of bumping the latter to multiple yet later versions, such as 5 and 6.x.
The currently used version (2.4) should also still be kept, for a while.
Bumping such versions will likely require some Elasticsearch client code
adaptations, so that Gerrit can (dynamically?) switch between either
Elasticsearch server version to eventually support (hopefully soon).
Doing the same for the elasticsearch tests in Gerrit is to be done using
another change or more changes.
Add a partial and customized fork of [1], based on [1]'s commit [2], to
preserve the ability of building proper json requests for Elasticsearch.
Put that forked json-generating code under a new 'builders' sub-package.
There should be a possibility in some near future to consider removing
that fork, based on potential progress such as the one proposed in [3].
Meanwhile, this fork shall be maintained to usual Gerrit quality levels.
[1] https://github.com/elastic/elasticsearch
[2] tag: v2.4.4
[3] https://github.com/elastic/elasticsearch/issues/30791
Bug: Issue 6094
Change-Id: I720c9885c9eab2388acc328eecb9eaa6940ced0c
f9758fd8bb