RFR: 8256397: MultipleSelectionModel throws IndexOutOfBoundException [v3]

[Florian Kirmaier]

> Fixing IndexOutOfBoundsException in the MultipleSelectionModelBase and added a unit-test for it.
> ticket: https://bugs.openjdk.java.net/browse/JDK-8256397
> run test: `./gradlew --continue -PFULL_TEST=true controls:test --tests "*MultipleSelectionModelImplTest*"`

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

  JDK_8256397
  Added a small test-factory, to test more cases

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/353/files
  - new: https://git.openjdk.java.net/jfx/pull/353/files/2f6dd153..42807262

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=353&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=353&range=01-02

  Stats: 7 lines in 1 file changed: 5 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jfx/pull/353.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/353/head:pull/353

PR: https://git.openjdk.java.net/jfx/pull/353