java.net.URLClassLoader.close() doesn't work as expected for JAR archives on
Windows.

The system resource held by URLClassLoader (i.e. JAR archive itself) is NOT
released even when the class loader is closed. A similar issue has been
fixed by JDK-6896088. This issue is regarded as a special case fixed by
JDK-6896088, which can be observerd when close() is called during exception
handling of load().

Issue reproducible in JDK 14, 11, 8 and 7. 7u131 is the oldest of these.
Steps to reproduce are below.

1. Creates a arbitrary JAR file
> ls
Main.java Main.class
> jar tvf sample.jar Main.class
> ls
Main.java Main.class sample.jar

2. Run the Main class. It does the following:
  a. Creates URLClassLoader and uses it to load a class from the JAR
  b. Calls close() when the Exception thrown
  c. Attempts to delete the JAR, but can not.

> java.exe --show-version Main
java 13 2019-09-17
Java(TM) SE Runtime Environment (build 13+33)
Java HotSpot(TM) 64-Bit Server VM (build 13+33, mixed mode, sharing)
java.nio.file.FileSystemException: sample.jar: The process cannot access the
file because it is being used by another process.

        at java.base/sun.nio.fs.WindowsException.translateToIOException(WindowsException.java:92)
        at java.base/sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:103)
        at java.base/sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:108)
        at java.base/sun.nio.fs.WindowsFileSystemProvider.implDelete(WindowsFileSystemProvider.java:274)
        at java.base/sun.nio.fs.AbstractFileSystemProvider.delete(AbstractFileSystemProvider.java:105)
        at java.base/java.nio.file.Files.delete(Files.java:1145)
        at Main.main(Main.java:21)

Test code:
=======================================================================
import java.io.*;
import java.net.*;
import java.nio.file.*;

public class Main {
   final static String FILE_NAME = "sample.jar";

   public static void main(String args[]) {
       URLClassLoader loader = null;
       URL url = null;
       Path path = Paths.get(FILE_NAME);
       try {
           String path_str = path.toUri().toURL().toString();
           url = new URL("jar", "", path_str + "!/" + "classes/");
           loader = new URLClassLoader(new URL[] { url });
           loader.loadClass("DUMMY");
       } catch (Exception e) {
       } finally {
           try {
               loader.close();
               Files.delete(path);
           } catch (IOException e) {
               e.printStackTrace();
           }
       }

   }
}
=======================================================================