How to set a Strategy for a ClassRealm?

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When I take a look at the ClassRealm code, I can see that there is only one place where the strategy is set.

public ClassRealm(ClassWorld world, String id, ClassLoader baseClassLoader) {
    super(new URL[0], baseClassLoader);

    this.world = world;

    this.id = id;

    foreignImports = new TreeSet<>();

    strategy = StrategyFactory.getStrategy(this);

    lockMap = isParallelCapable ? new ConcurrentHashMap<>() : null;

    if (isParallelCapable) {
        // We must call super.getClassLoadingLock at least once
        // to avoid NPE in super.loadClass.
        super.getClassLoadingLock(getClass().getName());
    }
}

This place uses the StrategyFactory.getStrategy(this) method, which is a static call. The StrategyFactory does not provide any mechanism to change the behavior, like ServiceLoader or a ThreadLocal.

So how can one set a strategy without using reflection to set the private field?
If noone can ever set a strategy, what is the purpose of the subclasses like OsgiBundleStrategy.