Update ExtensionTool.java

[HelgeStenstrom]

getFileExtension() doesn't return null, so we don't have to check for it.

[goxr3plus]

@HelgeStenstrom

Have you tested this with files that have no extension :) ?

[HelgeStenstrom]

No, I haven't tested it, I have just studied the code.
IntelliJ says that extension != null is always true.
extension is never null, because IOInfo.getFileExtension(fileName) never returns null.
IOInfo.getFileExtension(fileName) never returns null, because String.toLowerCase() never returns null.

[goxr3plus]

I will check it with real files soon to see every case , thanks :)