GH-8659: Fix the WatchServiceDirectoryScanner to detect new file afte…

[pziobron]

Fix the WatchServiceDirectoryScanner to detect new file after renaming the sub-folder of the watched folder (Java 7 WatchService)

[artembilan]

All looks good, however I would like to suggest some change to the file.adoc.
Go to the [[watch-service-directory-scanner]] section and explain there in the end that we need to track also WatchEventType.MODIFY and WatchEventType.DELETE event types if sub-directories can be renamed.

[artembilan]

The test has failed, probably due to your change:

WatchServiceDirectoryScannerTests > testWatchServiceDirectoryScanner() FAILED
    java.lang.AssertionError at WatchServiceDirectoryScannerTests.java:220

Please, revise.

[pziobron]

The fix seems to solve the problem on Windows - the files are detected properly in the sub-folder (of the watched folder) after renaming it.
I've tried to write a test for this scenario but it is hard to emulate it in Java (creating empty folder in File Explorer and renaming it). I am not sure if that's even possible.
I will experiment with that a bit :)

I will update documentation tomorrow...

[pziobron]

I've tried to replicate the issue in Java in order to write the Integration test which covers that issue.
Unfortunately, I haven't managed to do that.
I've been using:

1. File.mkdir()
2. File.renameTo(...)/Files.move(...)
3. File.createTempFile(...)

with no success - the file in sub-directory is detected properly.

The issue can be replicated in Windows with the File Explorer or with the Command Line by using the following commands:

1. md test1
2. move test1 test2
3. copy someFile test2

Theoretically, the Runtime.getRuntime().exec(...) could be used for the integration test but it would work obviously only for Windows (or for all Os'es when mapping md -> mkdir, copy -> cp etc....).
Nevertheless, I am not sure if that is a good idea (this could be tricky) ?

I've updated the documentation as You requested.

[artembilan]

... and cherry-picked to 6.1.x, 6.0.x & 5.5.x.

@pziobron ,

thank you for contribution; looking forward for more!