this.imageExtention = imageExtention;
            this.expiry = expiry;
            this.fessConfig = ComponentUtil.getFessConfig();
            this.maxPurgeSize = fessConfig.getPageThumbnailPurgeMaxFetchSizeAsInteger();
            this.searchEngineClient = ComponentUtil.getSearchEngineClient();
        }

        protected void deleteFiles() {
            final Map<String, Path> deleteFileMap = new HashMap<>();