RFR: 8343150: Change URLClassLoader.getPermissions to return empty PermissionCollection [v4]

[Jaikiran Pai]

> Can I please get a review of this change which removes the `getPermissions()` method from the `URLClassLoader`? This addresses https://bugs.openjdk.org/browse/JDK-8343150.
> 
> With the SecurityManager implementation removed through JEP 486, this method of the `URLClassLoader` is no longer relevant.
> 
> No new tests have been added. tier1 and tier2 testing is currently in progress.

Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:

  Daniel's suggestion - minor javadoc update

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22179/files
  - new: https://git.openjdk.org/jdk/pull/22179/files/7110654f..0b58479d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22179&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22179&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/22179.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22179/head:pull/22179

PR: https://git.openjdk.org/jdk/pull/22179