RFR: 8312630: java/security should not create unmodifiable collections with redundant wrapping [v2]

[John Jiang]

> Some java/security classes apply the below coding style,
> 
> Set<T> set = ...;
> Set<T> unmodifiableSet = Collections.unmodifiableSet(new HashSet<>(set));
> 
> It may be unnecessary to wrap that `set` with HashSet before creating `unmodifiableSet`.
> Some usages on `Collections.unmodifiableList` and `Collections.unmodifiableMap` have the same issue.

John Jiang has updated the pull request incrementally with one additional commit since the last revision:

  use copyOf instead of modifiableXXX

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15008/files
  - new: https://git.openjdk.org/jdk/pull/15008/files/64f607da..b8f2d9e0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15008&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15008&range=00-01

  Stats: 11 lines in 4 files changed: 0 ins; 2 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/15008.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15008/head:pull/15008

PR: https://git.openjdk.org/jdk/pull/15008