Fires when specified files do not exist. The file not exist trigger periodically scans, as defined by setPollingDelay(), the appropriate file system and fires when no files on the file system match the file criteria. In other words, the trigger fires when all files specified by the file criteria are non-existent.
NOTE: The File Not Exist trigger always assumes that the information specified in the File Criteria refers to filenames. If you specify '/My/Folder' in the File Criteria, the File Not Exist trigger will check that no files are named 'Folder', and will fire accordingly.