If present, only return notifications with this detection category. Categories are BRAND_MATCH, DETECTED_DOMAIN, DETECTED_IP, DETECTED_URL, DOMAIN_TYPOSQUATTING, FAVICON_REUSE, FILE_COMMUNICATING_WITH_DOMAIN, FILE_COMMUNICATING_WITH_IP, FILE_COMMUNICATING_WITH_URL, FILE_DOWNLOADED_FROM_DOMAIN, FILE_DOWNLOADED_FROM_IP, FILE_DOWNLOADED_FROM_URL, PATTERN_EMBEDDED_IN_FILE, SUBDOMAIN_ABUSE.