@Override
        public String toString() {
            return MoreObjects.toStringHelper(this).add("filePath", filePath).toString();
        }
Returns the file path associated with the current key. The path is used to unregister
from the {@link WatchService}.

@return the path associated with the current key
core/src/main/java/com/linecorp/armeria/client/endpoint/FileWatcherRegistry.java