RFR: 8375561: Class NGGroup is in need of some cleanup [v2]

[Christopher Schnick]

> This should improve the code quality of the class while preserving its original workings

Christopher Schnick has updated the pull request incrementally with three additional commits since the last revision:

 - Remove space
 - Use for loops again
 - Remove unused method

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/2043/files
  - new: https://git.openjdk.org/jfx/pull/2043/files/d0814ea8..898af0f9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=2043&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=2043&range=00-01

  Stats: 24 lines in 1 file changed: 1 ins; 17 del; 6 mod
  Patch: https://git.openjdk.org/jfx/pull/2043.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/2043/head:pull/2043

PR: https://git.openjdk.org/jfx/pull/2043