Back in 2005, I wrote a jtreg test to ensure that ZipFile handles entries with empty names properly. But it only tested getEntry, and not the enumeration returned from entries(), which indeed ends up throwing a NullPointerException in that case. Here's a fix for the test, and for the code.

Webrev: http://cr.openjdk.java.net/~martin/webrevs/openjdk9/ZipEntryEmptyName/