STORM-2191 shortens the worker classpath by substituting in wildcards for the full list of jars. The path is constructed using Paths.get(dir, "*"), but this doesn't work on Windows. It seems like Windows checks that the path is valid.
Paths doesn't guarantee support for globs, and we don't want the OS to examine the path in any case, since the wildcard isn't a "real" wildcard (including all files) but a special syntax for including jars in the Java classpath. The path should be constructed with String concatenation instead.