private void checkAndNotify() {
        if (System.currentTimeMillis() - lastCheckTimestamp < watchingPeriodInSec * 1000) {
            // Don't reach the period threshold, ignore this check.
            return;
        }

        boolean isChanged = false;
        for (final WatchedFile watchedFile : watchedFiles) {
            isChanged = isChanged || watchedFile.detectContentChanged();
        }
        if (isChanged) {
            List<byte[]> contents = new ArrayList<>(watchedFiles.size());
            watchedFiles.forEach(file -> {
                contents.add(file.fileContent);
            });
            try {
                notifier.filesChanged(contents);
            } catch (Exception e) {
                log.error("Files=" + this + " notification process failure.", e);
            }
        }
    }
Check file changed status, if so, send the notification.
oap-server/server-library/library-util/src/main/java/org/apache/skywalking/oap/server/library/util/MultipleFilesChangeMonitor.java