RFR: 8308588: Unnecessary synchronized on GTKStyle#ICONS_MAP can be removed

[Alisen Chung]

On Wed, 28 Aug 2024 08:54:39 GMT, Abhishek Kumar <abhiscxk at openjdk.org> wrote:

> `static final Map<String,GTKStockIcon> ICONS_MAP` is modified only in `static` block. Then [com.sun.java.swing.plaf.gtk.GTKStyle#get](https://github.com/kumarabhi006/jdk/blob/73f7a5f15dbba54a98f3916ff1190520ac07874d/src/java.desktop/share/classes/com/sun/java/swing/plaf/gtk/GTKStyle.java#L892) method read from it within `synchronized (ICONS_MAP)` block. As this map is read-only and all its content is initialized in static block we can safely remove synchronized from get call.

What's the benefit of removing synchronized from the get call? Also were tests run on all platforms that use GTK?

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PR Review: https://git.openjdk.org/jdk/pull/20741#pullrequestreview-2267314744