从 Java 调用 Kotlin 高阶函数

I have a Kotlin helper class defined as:

class CountdownTimer(endDateInSeconds: Long, callback: (timeRemaining: RemainingTime) -> Unit)

which as the name implies, takes an epoch time and a callback to be invoked at fixed intervals (seconds in this case) until the end date is reached. RemainingTime is a data class containing the amount of time (seconds, mins, hours etc) until the end date.

I can use this class from Kotlin cleanly:

        countdownTimer = CountdownTimer(endDate, { timeRemaining ->
             var timeString = // format time remaining into a string
             view?.updateCountdownTimer(timeString)
         })

However when I call this from Java, I am forced to provide an unnecessary return value in the callback, even though the anonymous function specifies a Unit return type (which in theory is the equivalent of a Java void return type):

        this.countdownTimer = new CountdownTimer(this.endDate, remainingTime -> {
             var timeString = // format time remaining into a string
             if (view != null) {
                 view.updateCountdownTimer(timeString);
             }
             return null;
        });

虽然从技术上讲这不是一个问题，但不得不从Java回调中提供一个毫无意义的返回值似乎..错误的在Kotlin中有没有更好的方式来表达这个回调？