git: openjdk/mobile: 8241883: (zipfs) SeekableByteChannel:close followed by SeekableByteChannel:close will throw an NPE coverage

[duke]

Changeset: 93831d4e
Author:    Lance Andersen <lancea at openjdk.org>
Date:      2020-04-10 14:00:01 +0000
URL:       https://git.openjdk.java.net/mobile/commit/93831d4e

8241883: (zipfs) SeekableByteChannel:close followed by SeekableByteChannel:close will throw an NPE coverage

Reviewed-by: clanger, alanb

! src/jdk.zipfs/share/classes/jdk/nio/zipfs/ByteArrayChannel.java
! src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystem.java
! test/jdk/jdk/nio/zipfs/testng/test/ChannelTests.java