Java Spliterator implementation for a sliding window stream handling

SlidingWindowSpliterator.java

import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.Objects;
import java.util.Queue;
import java.util.Spliterator;
import java.util.function.Consumer;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

public final class SlidingWindowSpliterator<T> implements Spliterator<Stream<T>> {

  private final Queue<T> windowBuffer;
  private final Iterator<T> sourceIterator;
  private final int windowSize;
  private final int size;

  public SlidingWindowSpliterator(Collection<T> source, int windowSize) {
    this.windowBuffer = new ArrayDeque<>(windowSize);
    this.sourceIterator = Objects.requireNonNull(source).iterator();
    this.windowSize = windowSize;
    this.size = calculateSize(source, windowSize);
  }

  @Override
  @SuppressWarnings("unchecked")
  public boolean tryAdvance(Consumer<? super Stream<T>> action) {
    if (windowSize < 1) {
      return false;
    }

    while (sourceIterator.hasNext()) {
      windowBuffer.add(sourceIterator.next());
      if (windowBuffer.size() == windowSize) {
        // arrays in java...
        action.accept(Arrays.stream((T[]) windowBuffer.toArray(new Object[0])));
        windowBuffer.poll();
        return sourceIterator.hasNext();
      }
    }

    return false;
  }

  @Override
  public Spliterator<Stream<T>> trySplit() {
    return null;
  }

  @Override
  public long estimateSize() {
    return size;
  }

  @Override
  public int characteristics() {
    return ORDERED | SIZED | NONNULL;
  }

  private int calculateSize(final Collection<T> source, final int windowSize) {
    if (source.size() < windowSize) {
      return 0;
    }

    return source.size() - windowSize + 1;
  }

  public static <T> Stream<Stream<T>> stream(final Collection<T> source, final int windowSize) {
    return StreamSupport.stream(new SlidingWindowSpliterator<>(source, windowSize), false);
  }
}