RFR: 8301604: Replace Collections.unmodifiableList with List.of [v3]

[Glavo]

> `List.of` is cleaner, and can slightly reduce the memory footprint for lists of one or two elements.
> 
> Because `List.of` can only store non-null elements, I have only replaced a few usage.
> 
> Can someone open an Issue on JBS for me?

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

  reformat

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1012/files
  - new: https://git.openjdk.org/jfx/pull/1012/files/33e22df6..4442eb09

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1012&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1012&range=01-02

  Stats: 14 lines in 1 file changed: 2 ins; 6 del; 6 mod
  Patch: https://git.openjdk.org/jfx/pull/1012.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/1012/head:pull/1012

PR: https://git.openjdk.org/jfx/pull/1012