If we conditionally do random things, e.g. initialize a node only after the first test, we have to make sure that we unconditionally create a new seed calling random.nextLong(), then initialize the node under a private randomness context. This makes sure that any random usage through Randomness.get() will retrieve the proper random instance through RandomizedContext.current().getRandom(). When running under private randomness, the context will return the Random instance that was created with the provided seed (forked from the main random instance) rather than the main Random that's exposed to tests as well. Otherwise tests become non repeatable because that initialization part happens only before the first executed test.

If we conditionally do random things, e.g. initialize a node only after the first test, we have to make sure that we unconditionally create a new seed calling random.nextLong(), then initialize the node under a private randomness context. This makes sure that any random usage through Randomness.get() will retrieve the proper random instance through RandomizedContext.current().getRandom(). When running under private randomness, the context will return the Random instance that was created with the provided seed (forked from the main random instance) rather than the main Random that's exposed to tests as well. Otherwise tests become non repeatable because that initialization part happens only before the first executed test.

If we conditionally do random things, e.g. initialize a node only after the first test, we have to make sure that we unconditionally create a new seed calling random.nextLong(), then initialize the node under a private randomness context. This makes sure that any random usage through Randomness.get() will retrieve the proper random instance through RandomizedContext.current().getRandom(). When running under private randomness, the context will return the Random instance that was created with the provided seed (forked from the main random instance) rather than the main Random that's exposed to tests as well. Otherwise tests become non repeatable because that initialization part happens only before the first executed test.

If we conditionally do random things, e.g. initialize a node only after the first test, we have to make sure that we unconditionally create a new seed calling random.nextLong(), then initialize the node under a private randomness context. This makes sure that any random usage through Randomness.get() will retrieve the proper random instance through RandomizedContext.current().getRandom(). When running under private randomness, the context will return the Random instance that was created with the provided seed (forked from the main random instance) rather than the main Random that's exposed to tests as well. Otherwise tests become non repeatable because that initialization part happens only before the first executed test.

* master:
  Simplify Unicast Zen Ping (elastic#22277)
  Replace IndicesQueriesRegistry (elastic#22289)
  Fixed document mistake and fit for 5.1.1 API
  [TEST] improve error message in ESTestCase#assertWarnings
  [TEST] remove deleted test classes from checkstyle suppressions
  [TEST] make ESSingleNodeTestCase tests repeatable (elastic#22283)
  Link for setting page in elasticsearch.yml is outdated
  Factor out sort values from InternalSearchHit (elastic#22080)
  Add ID for percolate query to Java API docs
  x_refresh.yaml tests should use unique index names and doc ids to ease debugging
  IndicesStoreIntegrationIT should not use start recovery sending as an indication that the recovery started
  Added base class for testing aggregators and some initial tests for `terms`, `top_hits` and `min` aggregations.
  Add link to foreach processor to ingest-attachment.asciidoc