RFR JDK-8149769: Null pointer exception in ZipFileSystemProvider

[Steve Drach]

Hi,

Please review this simple fix to ZipFileSystemProvider.  The issue is 
JDK-8149769 <https://bugs.openjdk.java.net/browse/JDK-8149769>.  I didn’t do a 
webrev but instead provide the following patch.

Thanks
Steve

diff -r 2d6c2c75f338 
src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystemProvider.java
--- a/src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystemProvider.java      
Tue Feb 09 14:07:28 2016 -0800
+++ b/src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystemProvider.java      
Fri Feb 12 12:59:46 2016 -0800
@@ -100,7 +100,7 @@
             }
             ZipFileSystem zipfs = null;
             try {
-                if (env.containsKey("multi-release")) {
+                if (env != null && env.containsKey("multi-release")) {
                     zipfs = new JarFileSystem(this, path, env);
                 } else {
                     zipfs = new ZipFileSystem(this, path, env);