HttpURLConnectionDownloaderService: improve warning message.

No code changes.

[ci skip]

Author: php-coder

src/main/java/ru/mystamps/web/service/HttpURLConnectionDownloaderService.java

@@ -116,7 +116,7 @@ private static HttpURLConnection openConnection(URL url) throws IOException {
 			LOG.warn(
 				"Couldn't open connection: "
 				+ "unknown type of connection class ({}). "
-				+ "Downloading images from external servers won't work!",
+				+ "Downloading files from external servers won't work!",
 				connection
 			);
 			return null;