I have been thinking about how to go about getting the file extension and came up with the following method using a substring. 
```public static String getExtension(String s) {
	    String ext = null;
	    int i = s.lastIndexOf('.');
	    if (i > 0 &&  i < s.length() - 1) {
	        ext = s.substring(i+1).toLowerCase();
	    }
	    return ext;
	}```
I know that this method does not incorporate the security of checking the mime type, but I imagine it will work for varying lengths of file extensions. It could be placed in, and called from the FeedUtils class as I assume it would be considered a utility method. What do you think?