An InvalidPathException is thrown by Class.getResource(String) by the following program when launched on Windows using the module path with exploded elements:

`mod/module-info.java`
```
module mod {}
```

`mod/pac/Main.java`
```
  package pac;
  class Main {
    public static void main(String... args) {
      Main.class.getResource("a"); // -> null
      Main.class.getResource(":"); // -> null | InvalidPathException
    }
  }
```

> javac -d classes --module-source-path . --module mod

> java --module-path classes --module mod/pac.Main
Exception in thread "main" java.nio.file.InvalidPathException: Illegal char <:> at index 4: pac\:
        at java.base/sun.nio.fs.WindowsPathParser.normalize(WindowsPathParser.java:182)
        at java.base/sun.nio.fs.WindowsPathParser.parse(WindowsPathParser.java:153)
        at java.base/sun.nio.fs.WindowsPathParser.parse(WindowsPathParser.java:77)
        at java.base/sun.nio.fs.WindowsPath.parse(WindowsPath.java:92)
        at java.base/sun.nio.fs.WindowsFileSystem.getPath(WindowsFileSystem.java:232)
        at java.base/jdk.internal.module.Resources.toSafeFilePath(Resources.java:143)
        at java.base/jdk.internal.module.Resources.toFilePath(Resources.java:97)
        at java.base/jdk.internal.module.ModuleReferences$ExplodedModuleReader.find(ModuleReferences.java:382)
        at java.base/jdk.internal.loader.BuiltinClassLoader.findResource(BuiltinClassLoader.java:497)
        at java.base/jdk.internal.loader.BuiltinClassLoader.findResource(BuiltinClassLoader.java:277)
        at java.base/java.lang.Class.getResource(Class.java:2927)
        at mod/pac.Main.main(Main.java:5)

A work-around is running the program on the class path:

> java --class-path classes/mod pac.Main

Another work-around is to archive the program and run it on the module path:

> jar --create --file mod.jar -C classes/mod .

> java --module-path mod.jar --module mod/pac.Main