When compiling JavaFX with Java 25, a new warning appears. This warning will result in a compilation failure because warnings are treated as error (-Werror).

The following warning appears:

> Task :controls:compileJava
C:\..\jfx\modules\javafx.controls\src\main\java\javafx\scene\control\SplitPane.java:320: warning: [identity] use of a value-based class with an operation that expects reliable identity
    private final WeakHashMap<Integer, Double> dividerCache = new WeakHashMap<>();
                                                                             ^
C:\..\jfx\modules\javafx.controls\src\main\java\javafx\scene\control\SplitPane.java:320: warning: [identity] use of a value-based class with an operation that expects reliable identity
    private final WeakHashMap<Integer, Double> dividerCache = new WeakHashMap<>();
                             ^
error: warnings found and -Werror specified
1 error
2 warnings

> Task :controls:compileJava FAILED

The warning makes sense: We use a WeakHashMap with the Integer class. So the Integer values are saved as WeakRef inside the Map. This makes no sense and is rightfully a warning.