isRegularFile checks for regular files, not directories...
MODIFY
src/main/java/org/apache/commons/io/FileUtils.java
src/main/java/org/apache/commons/io/FileUtils.java
@@ -1866,7 +1866,7 @@ public static boolean isFileOlder(final File file, final long timeMillis) {
* @param file the path to the file.
* @param options options indicating how symbolic links are handled
* @return {@code true} if the file is a regular file; {@code false} if
- * the path is null, the file does not exist, is not a directory, or it cannot
+ * the path is null, the file does not exist, is not a regular file, or it cannot
* be determined if the file is a regular file or not.
* @throws SecurityException In the case of the default provider, and a security manager is installed, the
* {@link SecurityManager#checkRead(String) checkRead} method is invoked to check read

isRegularFile checks for regular files, not directories...