RFR: 8348308: Make fields of ListSelectionEvent final

[Abdelhak Zaaim]

On Wed, 22 Jan 2025 20:20:28 GMT, Alexey Ivanov <aivanov at openjdk.org> wrote:

> The fields of `ListSelectionEvent` are set in the constructor and are never modified, mark the fields — `firstIndex`, `lastIndex`, `isAdjusting` — with the `final` modifier.

Thank you for making the fields final, improving immutability and thread-safety. However, the file header still references the copyright year as 2014. Please update it to 2025 to reflect the changes.

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PR Review: https://git.openjdk.org/jdk/pull/23243#pullrequestreview-2568224478