Purpose of class name comparison in compareTo?

[dclements]

At a few points in the code compareTo is implemented with the following pattern:

if (e instanceof SomeClass) {
    //Standard compareTo check.
} else {
    return getClass().getName().compareTo(e.getClass().getName());
}

What is this pattern supposed to be looking for?

[dclements]

Marking as a duplicate of #40, since the underlying issue seems to be the mixing of different types of comparison.