RFR: 8358526: Clarify behavior of java.awt.HeadlessException constructed with no-args

[Alisen Chung]

On Wed, 18 Jun 2025 17:57:26 GMT, Phil Race <prr at openjdk.org> wrote:

> Clarify the behaviour of new HeadlessException().getMessage()
> The spec. is updated to be clear that empty means null, not an empty string.

src/java.desktop/share/classes/java/awt/HeadlessException.java line 1:

> 1: /*

do copyright years need to be updated for this file if there's a docs change?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25881#discussion_r2159666300