[jdk11u-dev] RFR: 8231454: File lock in Windows on a loaded jar due to a leak in Introspector::getBeanInfo

[Basil Crow]

Hi all,

This pull request contains a backport of [JDK-8231454](https://bugs.openjdk.java.net/browse/JDK-8231454) (openjdk/jdk at 2ee2b4ae19d).

There was a trivial merge conflict in `Introspector.java`.

The commit being backported was authored by @mrserb on October 20, 2020, and was reviewed by @azuev-java.

See [JENKINS-63766](https://issues.jenkins.io/browse/JENKINS-63766) for the motivation behind this backport.

I tested this PR locally by running `make run-test TEST=test/jdk/java/beans/Introspector/FlushClassInfoCache.java`. In addition, I verified that JENKINS-63766 could no longer be reproduced with this backport applied.

Thanks!

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Commit messages:
 - 8231454: File lock in Windows on a loaded jar due to a leak in Introspector::getBeanInfo

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/1103/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=1103&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8231454
  Stats: 113 lines in 3 files changed: 109 ins; 1 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/1103.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/1103/head:pull/1103

PR: https://git.openjdk.java.net/jdk11u-dev/pull/1103