The downport of JDK-8234011 contained the test "test/jdk/jdk/nio/zipfs/ReleaseDeflater.java" which had to be slightly modified for the downport. These modifications made him fail on Windows.

The fix is trivial:

diff -r 11a23282c887 test/jdk/jdk/nio/zipfs/ReleaseDeflater.java
--- a/test/jdk/jdk/nio/zipfs/ReleaseDeflater.java Wed Aug 05 12:52:33 2020 +0300
+++ b/test/jdk/jdk/nio/zipfs/ReleaseDeflater.java Fri Sep 04 15:15:19 2020 +0200
@@ -48,7 +48,7 @@
 public class ReleaseDeflater {
     public static void main(String[] args) throws Throwable {
         Path zipFile = Paths.get("ReleaseDeflaterTest.zip").toAbsolutePath();
- URI zipURI = URI.create("jar:file:" + zipFile);
+ URI zipURI = URI.create("jar:" + zipFile.toUri());
         try (FileSystem fs = FileSystems.newFileSystem(zipURI, Map.of("create", "true"))) {
             FileSystemProvider zprov = fs.provider();
             Path test = fs.getPath("test.txt");