Static inner classes not visible to child classes

If both the parent class and the child are in the same file or project (i.e. they are being compiled together), this works; however, if the parent is compiled into a separate JAR, the child class is unable to see the parents inner classes.

Example:

class X {
    static class Y {}
}

Compile X into a separate JAR.

class Z extends X {
    Z() {
        Y y = new Y();
    }
}

Compiling Z will cause an error.