RFR: 8274597: Some of the dnd tests time out and fail intermittently [v4]

[Manukumar V S]

> These dnd tests fails with a time out intermittently in some machines(mostly Windows 11) which creates frequent noise in CI.
> 1. java/awt/dnd/AcceptDropMultipleTimes/AcceptDropMultipleTimes.java
> 2. java/awt/dnd/DropTargetEnterExitTest/MissedDragExitTest.java
> 3. java/awt/dnd/DropTargetEnterExitTest/ExtraDragEnterTest.java
> 4. java/awt/dnd/MissingDragExitEventTest/MissingDragExitEventTest.java
> 
> Issue :
> This doesn't seem to be a deadlock. When there is no sufficient delay after the mouse release(dragged mouse pointer release to drop the content), the frame is getting disposed even before the drop() method gets called. So it waits for the drop() method which will never happen as the frame has been already disposed and the test times out after some time.
> 
> Fix:
> Waiting for the drop() method to get called before disposing the frame.
> 
> Testing: 
> 1. All the four tests are run 10 times per platform and got all pass
> 2. All the four tests are run 10 times on Windows 11 and got all pass

Manukumar V S has updated the pull request incrementally with one additional commit since the last revision:

  Removed extra blank line added to Util, no changes required in Util

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8316/files
  - new: https://git.openjdk.java.net/jdk/pull/8316/files/e0d63537..fae1d36a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8316&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8316&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8316.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8316/head:pull/8316

PR: https://git.openjdk.java.net/jdk/pull/8316