BackOffExecution execution = backOff.start();
BackOffExecution execution2 = backOff.start();
assertEquals(2000l, execution.nextBackOff());
assertEquals(2000l, execution2.nextBackOff());
assertEquals(4000l, execution.nextBackOff());
assertEquals(4000l, execution2.nextBackOff());
assertEquals(BackOffExecution.STOP, execution.nextBackOff());
assertEquals(BackOffExecution.STOP, execution2.nextBackOff());
}