INT-3518: Upgrade versions and some cleanup

JIRA: https://jira.spring.io/browse/INT-3518
INT-3515: Fix Some WebSockets Issues

JIRA: https://jira.spring.io/browse/INT-3515

Change test suite to the Tomcat according IO

INT-3515: IllegalStateException for the `WebSocketInboundChannelAdapter`, when `useBroker = true`, but there is no Broker Relay in the Context
INT-3522: MQTT XSD: Fix client-factory attr type

JIRA: https://jira.spring.io/browse/INT-3522
INT-3511: Document WebSocket Support

JIRA: https://jira.spring.io/browse/INT-3511

Add note about Broker destinations

Doc Polishing

INT-3511: Fix 'useBroker' Docs and provide compatibility with SF 4.1.1
INT-3524 Fix Tooling MessageChannel References

JIRA: https://jira.spring.io/browse/INT-3524

A number of references (expected-type) still referred to
the Spring Integration 3.0 MessageChanel.
INT-3526 Used Expanded URI In Exception Message

JIRA: https://jira.spring.io/browse/INT-3526

Previously, the URI in the exception message is the raw
URI with placeholders, if present.

Use the expanded URI in the message instead.
INT-3512: Add `<advice-chain>` to the Aggregator

JIRA: https://jira.spring.io/browse/INT-3512

INT-3512: Fix typos

INT-3512: add `expire-` prefix to the advice sub-elements

INT-3512: Mark `AggregatorWithCustomReleaseStrategyTests` as `LONG_RUNNING_TEST`

Doc Polishing
INT-3527: WebSocket and 'o-c-a' Improvements

JIRA: https://jira.spring.io/browse/INT-3527

* `WebSocketInboundChannelAdapter` now handles `CONNECT` STOMP message and sends `CONNECT_ACK` message to the `WebSocketSession` immediately
* `ExpressionMessageProducerSupport` implementations now checks the result of `expression` and if it is a `Message<?>` it is sent to channel without creating a new one
which previously wrapped that `Message<?>` as the `payload`.
* Add `<script>` support to the `<outbound-channel-adapter>`
* Upgrade to the SF 4.1.1
* Add appropriate notes to the Docs
INT-3528 Use Collections min and max methods where appropriate

JIRA: https://jira.spring.io/browse/INT-3528

Use `min` and `max` methods instead of sorting an entire collection to get the minimum or maximum element.

Change other inline `Comparator<?>`s to the `final` fields
INT-3531 Varargs for JavaMailSender

JIRA: https://jira.spring.io/browse/INT-3531

JavaMailSender now uses varargs instead of [].

Also, add spring-context-support as an optional
dependency to avoid reactor pulling in an old version into
the eclipse .classpath.

You cannot exclude transitive dependencies from optional
(reactor) dependencies.
INT-3529 Add 'expire-groups-upon-timeout' to Reseq

JIRA: https://jira.spring.io/browse/INT-3529

Late arriving messages will now be immediately discarded by
default.

INT-3529 Polishing

Move group completion to the Resequencer's `afterRelease()` when
the group is timed out.
Increase `receive` timeout for some tests

https://build.spring.io/browse/INT-B41-118

Since `send` to the `discardChannel` caused from the separate Thread (`TaskScheduler` from `groupTimeout`)
there is some time window when receiving thread wait on `queue` lock, so `0` timeout to wait isn't enough
Fix Docs issue

https://build.spring.io/browse/INT-B41-119
INT-3516: Allow `Optional<>` in POJO Method Args

JIRA: https://jira.spring.io/browse/INT-3516

* Add `Optional<>` support for `@Header` in the `MessagingMethodInvokerHelper`
* Add `Optional<>` test-case
* Change `sourceCompatibility` for test to the Java 8

INT-3516: Revert SF version to 4.1.1

Add Docs on the matter

Fix WS Tests; Revert StubJavaMailSender
INT-3520: Add Reactor's `PersistentQueue` Support

JIRA: https://jira.spring.io/browse/INT-3520

INT-3520: Use `Condition` to wait items in the `Queue`

INT-3520: Reworking to the `Semaphore(0)`

* Implement 'artificial infinite wait'
* Add distributed test with infinite `receive()`

INT-3520: Correct usage of `Semaphore`

Minor Doc Polishing
INT-3516 Fix JPA Build Error

https://build.spring.io/browse/INT-B41-121
INT-3519 Add Poll Skip Advice

JIRA: https://jira.spring.io/browse/INT-3519

Add a mechanism to allow skipping polls, perhaps
because of some downstream condition.

INT-3519: Polishing
INT-3536 Fix Mail Receiver Regression Issue

JIRA: https://jira.spring.io/browse/INT-3536

The fix for opening multiple IMAP connections in the idle
adapter inadvertently removed the check for the store being
open.

Add `connectStoreIfNecessary()` and test case.
INT-275: Implement Scatter-Gather Pattern

JIRA: https://jira.spring.io/browse/INT-275

In addition fix the `Lifecycle` issue in the `ServiceActivatorAnnotationPostProcessor`

Add Namespace support, Addition tests
   and fix some typos in the XSD

INT-275: Fix failed tests

INT-275: Fix for `replyChannel` Header

Add `sync` reply test-case

INT-275: Make `ScatterGatherHandler` sync

Fix some `MessageHandler`s from `SmartLifecycle`

INT-275: Fix `ScatterGatherHandler.handleRequestMessage` logic

INT-275: Fix `ScatterGatherHandler` JMX proxying issues

* Make `AbstractCorrelatingMessageHandler.getMessageStore()` as `public`
* Move `ScatterGatherHandlerIntegrationTests` to the JMX module to be sure that `ScatterGatherHandler`
works well with `@EnableIntegrationMBeanExport`
* Add xml config sample how to use an internal gatherer's `MessageStore` in the `MessageGroupStoreReaper`
* Add `What's New` notice
INT-3537 RemoteFileTemplate Close Stream

JIRA: https://jira.spring.io/browse/INT-3537

Stream not closed if session cannot be created.

Add `try {} finally {}`.

__cherry-pick to 4.0.x, 3.0.x__