reactor/reactor-core v3.2.6.RELEASE on GitHub

Reactor-Core 3.2.6.RELEASE is part of Californium-SR5} Release Train.

This is a recommended update for all Reactor 3 users.

⚠️ Update considerations and deprecations

ConsoleLogger doesn't log TRACE/DEBUG levels by default now (#1484)
- (note it is the default logging implementation when SLF4J isn't found)
- DEBUG/TRACE levels had potential for being a very verbose default, especially when using reactor-netty
- DEBUG/TRACE on console can be programmatically opted-in via Loggers.useVerboseConsoleLoggers()
- Use of JDK loggers instead of console can be activated at start up via setting reactor.logging.fallback system property to JDK

Flux.collect and friends (collectList, collectMap, collectMultiMap) now support doOnDiscard (#1510)
Scheduler#schedulePeriodically now accepts 0 delay and 0 duration periodic tasks (#1498)

Proactively avoid logging onNext(QueueSubscription) (#1515)
- We would previously rely on UnsupportedOperationException to detect cases of attempting to "deep-logging" an internal object as a Collection
- Log4J2 recently started swallowing all exceptions.
- We now eagerly convert the usual suspect (QueueSubscription) to a String before passing to logging implementation.
switchOnFirst has been improved
- It now better support case where one switches to an unrelated Publisher (#1517)
- source Flux will get cancelled at the termination of said unrelated publisher
- Despite cancellation, the operator would previously still trigger the switching BiFunction (#1502)
Mono#fromRunnable can now be cancelled immediately and withholds invoking the Runnable (#1503)
Fixed windowWhile/windowUntil cancellation when the resulting Flux is cancelled before the last in flight window (#1452)
mergeSequential's first inner sequence would not be cancelled with the rest when output Flux was cancelled (#1500)
usingWhen terminal callbacks are now mutually exclusive with the cancel one (#1487)

[doc] new marble diagrams have been introduced in this release (#1463, #1448)
- index,limitRequest,onBackpressureBuffer variant, sort, sequenceEquals, doFinally, doOnEach, switchOnFirst
[doc] Wording of switchOnFirst has been clarified, regarding the inclusion of first signal in the Flux passed to the BiFunction (#1514)
[doc] Fixed reactive-stream Gradle coordinates in reference documentation (#1505)
[build] Changed the way JApiCmp gets its baseline (don't rely on Gradle) (6ca1ae9)
[build] Adapt JDK javadoc links when building under JDK9-10 and JDK11+ (0788a2b)