When actual classpath includes folder that contains spaces, URLScanner throws an exception (java.io.FileNotFoundException). Problem is at line 93 where string holding URL is "converted" to path just by stripping URL scheme prefix. Unfortunately, spaces in URL are expressed either by plus sing or %20 escape sequence, which remains in file path instead of proper URL decoding. For example "file:/C:/with%20space" is converted to "/C:/with%20space" instead of "C:/with space".