RFR: 6858: Thread dump does not show complete call stack based for all threads (grouped by time)

[Suchita Chaturvedi]

Thread dump does not show complete call stack based on all threads (grouped by time) in first shot.

The user need to click on each sub sections of the sub-tree to see the corresponding thread dumps. But the user wanted
to see full thread dump in one shot as soon as they click on timestamp mentioned. Attached the screenshots of the
functionality before and after fix.


Before fix


<img width="690" alt="JMC_6170"
src="https://user-images.githubusercontent.com/11155712/85997486-2bd39980-ba27-11ea-824c-958c3adc0c96.png">

After fix

<img width="960" alt="JMC_6170_Fixed"
src="https://user-images.githubusercontent.com/11155712/85997520-35f59800-ba27-11ea-9cd5-73efe83a7102.png">

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

Commit messages:
 - 6858: Thread dump does not show complete call stack based for all threads (grouped by time)

Changes: https://git.openjdk.java.net/jmc/pull/90/files
 Webrev: https://webrevs.openjdk.java.net/jmc/90/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JMC-6858
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jmc/pull/90.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/90/head:pull/90

PR: https://git.openjdk.java.net/jmc/pull/90