Request for approval: JDK-8030050 Validate fields on DnD class deserialization

[Petr Pchelko]

Hello,

This is a request for approval to backport the fix from JDK-9 to JDK8u20.

The bug: https://bugs.openjdk.java.net/browse/JDK-8030050
The 9 changeset: http://hg.openjdk.java.net/jdk9/client/jdk/rev/0efdaaad9678

Thank you.
With best regards. Petr.