void unregister(FileWatchRegisterKey watchRegisterKey) {
        lock();
        try {
            final FileSystem fileSystem = watchRegisterKey.filePath().getFileSystem();
            final FileSystemWatchContext watchServiceContext = fileSystemWatchServiceMap.get(fileSystem);
            if (watchServiceContext == null) {
                return;
            }
            watchServiceContext.unregister(watchRegisterKey);
            if (!watchServiceContext.isRunning()) {
                fileSystemWatchServiceMap.remove(fileSystem);
            }
        } finally {
            unlock();
        }
    }
Stops watching a properties file corresponding to the {@link FileWatchRegisterKey}. Nothing
happens if the {@link FileWatchRegisterKey} is not registered or already unregistered. This
method is thread safe.
@param watchRegisterKey the key that was used to register for watching a file.
core/src/main/java/com/linecorp/armeria/client/endpoint/FileWatcherRegistry.java