Merge branch 'stable-2.14' into stable-2.15
* stable-2.14:
ElasticIndexVersionDiscovery: Convert to Java stream API
ElasticVersionManager: Use correct configuration value for prefix
Elasticsearch: Refactor generation of bulk requests
Rename AbstractReindexIT to AbstractReindexTests
ElasticReindexIT: Use @ConfigSuite.Default instead of @ConfigSuite.Config
UpdateRequest, added in I7156bc1e3 ("Elasticsearch: Refactor generation of
bulk requests"), is adapted to the removal of FillArgs in I0785c7e2c.
Change-Id: I30c8e259416e3acd6b61b1623e3a79fff3465edd