RFR: JDK-8236259: MemoryLeak in ProgressIndicator - DeterminateIndicator doesn't get collected

[Florian Kirmaier]

Hi everyone,

Here is my PR for the memory-leak I've reported some minutes ago.
PR: https://github.com/openjdk/jfx/pull/71
Ticket: https://bugs.openjdk.java.net/browse/JDK-8236259
The fix itself is quite straight forward.
It basically just removed the listener which causes the leak.

The unit-test for the fix is a bit more complicated.

I added a library JMemoryBuddy https://github.com/Sandec/JMemoryBuddy
(written by myself), which simplifies testing for memory leaks.
I think there are many places in the JavaFX-codebase that could highly
benefit from this library.
It could also simplify many of the already existing unit tests.
It makes testing for memory-leaks readable and reliable.
It would also be possible to just copy the code of the library into the
JavaFX-codebase.
It only contains a single class.

I also had to make a method public, to write the test. I'm open to ideas,
how I could solve it differently.

Florian Kirmaier