When this addon is installed and enabled, the sign will remember who placed it (without relying on an external data storage such as flat files, or a database), and only the owner of the sign can edit.
Installation:
Place ES-OwnershipCheck-x.x.x.jar file in plugins/EditableSign/addons folder.
Once you restart the server, EditableSign plugin will automatically integrate this addon into itself and auto-generates a default config file OwnershipCheck_config.yml.