hg: jdk/sandbox: 8228338: tools/pack200/TimeStamp.java fails with NullPointerException

[chris.hegarty at oracle.com]

Changeset: 45133b603c21
Author:    bpb
Date:      2019-07-18 07:54 -0700
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/45133b603c21

8228338: tools/pack200/TimeStamp.java fails with NullPointerException
Reviewed-by: lancea

! src/java.base/share/classes/com/sun/java/util/jar/pack/PackageReader.java
! src/java.base/share/classes/sun/net/www/content/text/plain.java