[NETBEANS-5181] Update NbBundle to read bundle files like JDK9 does (UTF-8 then ISO-8859-1)

[jjazzboss]

Changed NbBundle to read Bundle files using UTF-1 encoding by default, and
automatically switch to ISO-8859-1 if UTF-1 decoding fails. System property
java.util.PropertyResourceBundle.encoding can alter the behavior
like for PropertyResourceBundle (from JDK9).

[jjazzboss]

I checked the travis log, only 1 job failed "#8201.21 Test Java modules without nb-javac on Java 14". There are exceptions in several places, no idea which one is fatal, and it does not seem related to the code I've changed. Help is welcome...

[matthiasblaesing]

For the unittest: That job is flaky - I restartet the test.

For the commit:

Please adjust the title (it is UTF-8, not UTF-1). What I'm missing is a reasoning for the possible issues introduced by this change. How probable is it, that some one used a ISO-8859-1 char from the high range (with the highest bit set) and that that character (or this character and the following characters) form a valid UTF-8 sequence?

For example the sequence ˤ encoded as ISO-8859-1 will yield:

À       §
C   0   A   7
1100000010100111

That correctly decodes as UTF-8 to 삧 (Hangul Bbic). So this might introduce regressions.

How does the JDK handle this situation?

[lkishalmi]

A few unittest would be nice.
Well my guess on the regression is that can be so rare, than if noticed, specifying java.util.PropertyResourceBundle.encoding property explicitly, would solve the issue.

[jjazzboss]

Regarding the regression risk, my code has exactly the same approach than JDK.

I'll add a few unit tests.

[lkishalmi]

Something got here, needs to be fixed.

[jjazzboss]

done

[matthiasblaesing]

Looks ok to me. If I remember the number of bundles in the netbeans code base, I think preventing unnessary waste would be good. In that case, two static variables each holding an instance of Utf8ThenIsoCharset, one with acceptOnlyUTF8 and one without it set.

I left two additional inline comments.

[matthiasblaesing]

@jjazzboss thank you. I also double checked and this should indeed be save. To get this finished, a bit of work remains:

• I assume you read the comment at the top of the files you edited. Your change will also be considered a donation to the ASF, so I assume you are the author and agree to this donation.
• Please squash the commits into one commit and double check the author information. The name provided in the commits is looks good, but there are three different email addresses listed. Please use your personal address for committing.

If that is done, I'll let travis do its work and will then merge.

[jjazzboss]

@matthiasblaesing Yes I'm ok for the donation. I squashed the commits. Happy to complete my first PR :-)

[matthiasblaesing]

Thank you.