8319817: Charset constructor should make defensive copy of aliases

[toddjonker]

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Clean backport.

Additional testing:

• [x] New regression test fails without the fix, passes with it
• [x] macosx-aarch64-server-release: make test-tier1
• [x] linux-x86_64-server-release: JTREG_KEYWORDS="\!headful & \!external-dep & \!printer" make test TEST=all
  • These tests fail repeatedly, but also fail on master:
    • build/AbsPathsInImage.java
    • jdk/internal/platform/docker/TestDockerMemoryMetrics.java

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Progress

• [ ] JDK-8319817 needs maintainer approval
• [x] Change must not contain extraneous whitespace
• [x] Commit message must refer to an issue

Error

 ⚠️ OCA signatory status must be verified

Issue

• JDK-8319817: Charset constructor should make defensive copy of aliases (Bug - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk17u-dev.git pull/2713/head:pull/2713
$ git checkout pull/2713

Update a local copy of the PR:
$ git checkout pull/2713
$ git pull https://git.openjdk.org/jdk17u-dev.git pull/2713/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 2713

View PR using the GUI difftool:
$ git pr show -t 2713

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk17u-dev/pull/2713.diff