7143743: Potential memory leak with zip provider

Reviewed-by: lancea, clanger, alanb
Contributed-by: NJaikiran Pai <jai.forums2013@gmail.com>

src/share/demo/nio/zipfs/src/com/sun/nio/zipfs/ZipFileSystem.java

 /*
- * Copyright (c) 2009, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2009, 2020, Oracle and/or its affiliates. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -289,6 +289,14 @@ public class ZipFileSystem extends FileSystem {
                 def.end();
         }
 
+        beginWrite();                // lock and sync
+        try {
+            // Clear the map so that its keys & values can be garbage collected
+            inodes = null;
+        } finally {
+            endWrite();
+        }
+
         IOException ioe = null;
         synchronized (tmppaths) {
             for (Path p: tmppaths) {