JIRAs:
https://jira.spring.io/browse/INT-3830https://jira.spring.io/browse/INT-3523https://jira.spring.io/browse/INT-3846
* Fix the OOM condition, when we `release()` `UpperBound` independently of the previous `remove` result (https://jira.spring.io/browse/INT-3846)
* Fix "confuse" around `groupCapacity`, when we really didn't care about individual groups (https://jira.spring.io/browse/INT-3523)
* Add `upperBoundTimeout` to have a hook to wait some time for the empty slot in the store (https://jira.spring.io/browse/INT-3830)
* Fix some JavaDocs warnings
* Fix some typos
* Fix inconsistency in the `DelayHandler` around `removeMessageFromGroup` when `MS` is `SimpleMessageStore`
* Remove `UpperBound.release()` operation from `SimpleMessageStore.removeGroup()`.
The waiting process should worry about the new `UpperBound` instance.
Some other polishing
`tryAcquire` outside of the `lock`
Move `tryAcquire` within the `addMessageToGroup` outside of `lock`.
But do that only for groups which already exist.
For the new groups we have a fresh `UpperBound`, so no need to worry about dead lock and
we can obtain a permit immediately.
SimpleMessageGroup: BlockingQueue -> LinkedHashSet
`SimpleMessageStore`: use "unsynchonized" `SimpleMessageGroup`
Make some synchronization fixes according to the migration to the `LinkedHashSet`
Avoid extra `Collection`
`ResequencingMessageHandler`: compare `size()` of collections instead of `containsAll()`
Fix `ConcurrentModificationException` in the `AbstractKeyValueMessageStore`
Add `SimpleMessageStore.clearMessageGroup()`
Accept polishing and fix `RedisChannelMessageStoreTests`
`@Deprecated` `MessageGroupStore.removeMessageFromGroup()`
Fix some typos
Introduce `SimpleMessageGroupFactory`
Extract `MessageGroupFactory` and address PR comments
Polishing after rebase
JavaDocs and Reference Manual
Fix JavaDocs
201f0fc2b1