public boolean isAlive(E endpoint) {
        AtomicInteger attempts = pingAttempts.get(endpoint);
        return attempts != null && attempts.get() < maxPingAttempts;
    }
@Test
    public void member_isNotAlive_whenNoHeartbeat() {
        Member member = newMember(5000);
        assertFalse(failureDetector.isAlive(member));
    }