call Locale.getAvailableLocales() error

[zero he]

Version: jdk: oracle jdk1.8 okapi: 0.30 and 0.31

Exception in thread "main" java.lang.IllegalArgumentException: The locale identifier cannot be null or empty.
    at net.sf.okapi.common.LocaleId.normalize(LocaleId.java:425)
    at net.sf.okapi.common.LocaleId.<init>(LocaleId.java:327)
    at net.sf.okapi.common.LocaleId.getAvailableLocales(LocaleId.java:746)

[ysavourel]

Maybe something specific to Java 8: A simple call to LocaleId.getAvailableLocales() seems to work on Java 7. @nmihai_2000 : maybe something related to the new normalization.

[Mihai Nita]

Java 8 returns the "empty locale" as available locale. That is the Locale.ROOT

Java 7 also "knows" about the ROOT locale [https://docs.oracle.com/javase/7/docs/api/java/util/Locale.html#ROOT]

But it did not include it in the list of available locale.

This it not a problem anymore after the ICU refactoring.

Added a test unit, just in case (6e8c7f6)