ClassValue::remove does not halt ongoing computations. As a result, a later-installed value may not observe the state changes that happens-before the removal call if the computation began before the remove call, which is almost impossible to guarantee without external synchronization, defeating the point of ClassValue.

See example:

AtomicInteger input = new AtomicInteger(0);
ClassValue<Integer> cv = new ClassValue<>() {
    @Override
    protected Integer computeValue(Class<?> type) {
        // must get early to represent using outdated input
        int v = input.get();
        try {
            Thread.sleep(COMPUTE_TIME_MILLIS);
        } catch (InterruptedException ex) {
            throw new RuntimeException(ex);
        }
        return v;
    }
};
var innocuous = Thread.startVirtualThread(() -> cv.get(int.class));
var refreshInput = Thread.startVirtualThread(() -> {
    input.incrementAndGet();
    cv.remove(int.class); // Let's recompute with updated inputs!
});
try {
    innocuous.join();
    refreshInput.join();
} catch (InterruptedException ex) {
    throw new RuntimeException(ex);
}
assertEquals(1, input.get(), "input not updated");
assertEquals(1, cv.get(int.class), "CV not using up-to-date input");