java - JDK 15 密封类 - 如何跨包使用？

Question

我有一个简单的密封类，MyShape :

public sealed class MyShape permits MyCircle {

    private final int width;
    private final int height;

    public MyShape(int width, int height) {
        this.width = width;
        this.height = height;
    }

    public int width() {
        return width;
    }

    public int height() {
        return height;
    }
}

还有一个简单的子类， MyCircle :

public final class MyCircle extends MyShape {

    public MyCircle(int width) {
        super(width, width);
    }
}

当两个类都在同一个包中时，一切都会编译并运行。如果我将 MyCircle 移动到子包中，则构建会中断: java: class is not allowed to extend sealed class: org.example.MyShape .
我的理解来自 JDK 15 docs是这应该工作。我错过了一步吗？
我已经 created a GitHub repo如果你想尝试。

Answer 1

如您链接的文档中所述:
JDK 15 Documentation

They must be in the same module as the sealed class (if the sealed class is in a named module) or in the same package (if the sealed class is in the unnamed module).