static TimeWindow timeWindowForSize(final long startMs,
                                        final long windowSize) {
        long endMs = startMs + windowSize;

        if (endMs < 0) {
            LOG.warn("Warning: window end time was truncated to Long.MAX");
            endMs = Long.MAX_VALUE;
        }
        return new TimeWindow(startMs, endMs);
    }
Safely construct a time window of the given size,
taking care of bounding endMs to Long.MAX_VALUE if necessary
streams/src/main/java/org/apache/kafka/streams/state/internals/WindowKeySchema.java