Improve HttpSessionSecurityContextSessionRepository Performance

[spring-projects-issues]

Backport of gh-9387

[CaesarGao]

Looking at the commit history, it doesn't appear that the HttpSessionSecurityContextSessionRepository.java changes have been made to the 5.3.X line. The file still shows it was last modified 2 years ago.
Can see the change reflected in the 5.2.X and 5.4.X line.
Could you review and confirm.

[rwinch]

I wonder if the reason you cannot find the commit it is due to the fact this was incorrectly marked for 5.3.7 instead of 5.3.8? The commit is 38e9e8c Due to a problem with the release of 5.3.7 we used a release branch and the commit that made the change for the tag is 9a49a86

[CaesarGao]

Thanks, the branch 5.3.x looks okay with the commit 38e9e8c. But the commit 9a49a86 for tag 5.3.8.RELEASE seems only made changes for HttpSessionSecurityContextSessionRepositoryTest.java, HttpSessinoSecurityContextSessionRepository.java still remain the same.