Remove AbstractMessageListenerContainer.isPaused

[Wzy19930507]

Use AbstractMessageListenerContainer method isPauseRequested uniformly instead of isPaused().

[Wzy19930507]

I executed ./gradlew check again and executed TestOOMError multiple times, but can not reproduce the error in the image

[sobychacko]

I am not sure whether we should remove the isPaused method from the container API as it makes more sense than the isPauseRequested counterpart.

[Wzy19930507]

isPaused() use to adaptor resumed/paused, see spring-integration-kafka#198, after #609 container has two phase for paused/resume that isPauseRequested and isContainerPaused.

see #609 comment about isPaused()

it doesn't really reflect whether the container is actually paused yet, just that pause() has been called (it takes a little while before the actual pause occurs).

look like same as

	/**
	 * Return true if {@link #pause()} has been called; the container might not have actually
	 * paused yet.
	 * @return true if pause has been requested.
	 * @since 2.1.5
	 */
	default boolean isPauseRequested() {
		throw new UnsupportedOperationException("This container doesn't support pause/resume");
	}

[artembilan]

Yes. I totally agree with the change.

@sobychacko ,
please, proceed with the detailed review.

I'm not sure how that ConcurrentModificationException is possible: we have all the this.containers guarded by the this.lifecycleLock.lock() and I don't see any modifications from the outside in that test...

[sobychacko]

Looks like the tests are green now. I will do another pass of the review. Don't you think the isPaused removal deprecated first since its protected?

[artembilan]

I think the code is now like this in this PR:

@Deprecated(since = "3.2", forRemoval = true)
protected boolean isPaused() {

So, we are good.

[sobychacko]

Sorry, I missed that.