Bug#897945: #897945 still present/breaks with Java 8

[Per Lundberg]

FWIW, version 1.4.2-1 works correctly with openjdk-11-jdk version 
11.0.2+7-1, but it _does not_ work correct any more with Java 8 
(openjdk-8-jdk version 8u191-b12-2)

This worked correctly with 1.3.9-1 after downgrading the libnb-*-java 
packages as suggested by Ben - visualvm worked fine on Java 8 with this 
combination of packages.

So, we should either:

- Reopen the bug and fix the problem (likely by compiling visualvm with 
openjdk-8, which should make it work on newer JDK versions also)

- Accept the breakage and indicate this somehow, preferably in the 
package metadata. (I don't know if we can use dpkg dependencies in this 
case? It's perfectly legal to have both OpenJDK 11 and 8 _installed_ on 
a machine; it's just that the latter is unusable with visualvm from now on.)

Because the resolution here is not perfectly clear, I will refrain from 
just reopening the bug until it has been discussed a bit more.

Best regards,
--
Per