Work limiter for Java

WorkLimiter.java

import java.util.concurrent.TimeUnit

import static java.util.Arrays.asList
import static java.util.concurrent.TimeUnit.MILLISECONDS

/**
 * Limit amount of work according to the provided frequency limitations
 *
 * Note: Converted from Java
 */
 class WorkLimiter {

    private final List<FreqLimit> limits

    private final long startTimestamp

    private final SortedMap<Long, Integer> timestampToWorkCount

     WorkLimiter(FreqLimit... limits) {
        this(asList(limits))
    }

     WorkLimiter(List<FreqLimit> limits) {
        this.limits = new ArrayList<>(limits)
        this.startTimestamp = System.currentTimeMillis()
        this.timestampToWorkCount = new TreeMap<>()
    }

    /**
     * Record single (unit of) work and put the thread into sleep in case any of the limits has been reached in its current interval.
     * The thread will sleep as long as it cannot do the work due to any of the limits.
     *
     * @throws InterruptedException if the sleeping thread is interrupted
     */
     void limit() throws InterruptedException {
        long finished = System.currentTimeMillis()
        timestampToWorkCount.merge(finished, 1, Integer::sum)
        for (FreqLimit limit : limits) {
            long elapsedInWin = (finished - startTimestamp) % limit.inMillis()
            long winStart = finished - elapsedInWin
            int workInWin = timestampToWorkCount.tailMap(winStart).values().stream().mapToInt(Integer::intValue).sum()
            if (workInWin == limit.limit) {
                Thread.sleep(limit.inMillis() - elapsedInWin)
            }
        }
    }

     static class FreqLimit {

        private final int freqValue

        private final TimeUnit freqUnit

        private final int limit

         FreqLimit(int freqValue, TimeUnit freqUnit, int limit) {
            this.freqValue = freqValue
            this.freqUnit = freqUnit
            this.limit = limit
        }

        private long inMillis() {
            return MILLISECONDS.convert(freqValue, freqUnit)
        }
    }
}