The java source static analysis believes that done is not referenced in the "bad" method. Using "done = done |" rather than "done |=" works as expected.

public class FlowFailure {

    public static void bad(String... args) {
        boolean done = false;
        long counting = 0;
        while (!(done |= Thread.currentThread().isInterrupted())) {
            counting++;
            done = counting > 1_000_000_000;
        }
    }

    public static void good(String... args) {
        boolean done = false;
        long counting = 0;
        while (!(done = done | Thread.currentThread().isInterrupted())) {
            counting++;
            done = counting > 1_000_000_000;
        }
    }


}