RFR: 8246348: Crash in libpango on Ubuntu 20.04 with some unicode chars

[Kevin Rushforth]

On Thu, 11 Jun 2020 18:08:18 GMT, Phil Race <prr at openjdk.org> wrote:

>> This addresses https://bugs.openjdk.java.net/browse/JDK-8246348
>
> Instead of a space you could use a ZWNJ U+FEFF. Because that is also the endian-ness
> mark, Unicode actually prefers you now to use U+2060 but you need to make sure these
> are processed correctly by pango. Unlike a space they should have no rendering effect - not even an advance.

Once you address the question of storing a null value in the Map, the only remaining question I have is whether to use
a LinkedHashMap instead of an ordinary HashMap. In general, I like the predictability of a LinkedHashMap for maps that
are iterated, but in this case, I don't feel strongly about it one way or the other.

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PR: https://git.openjdk.java.net/jfx/pull/249