Notebook hangs when a static method signature is redefined

[andrus]

This may be an underlying JShell issue (or not), but I just noticed the following behavior with 1.0-a4 and Java 21:

1. Start with this cell:

static void a(String a) {
    display(a);
}

2. Execute it, call the function in some other cell... So far so good
3. Go back to the first cell and change the static method signature, and execute the cell:

static void a(Integer a) {
    display(a.toString());
}

At this point the notebook hangs forever and has to be restarted to get back to a working state: