Java includes only some 10 localizations for a variety of accessibility, look-and-feel and other resources of Java's runtime that are translated. Examples of such files are:
com\sun\java\swing\plaf\motif\resources\motif_ja.class
com\sun\swing\internal\plaf\basic\resources\basic_*.class
com\sun\swing\internal\plaf\metal\resources\metal_*.class
...

  Customers need a way to add/plug in more localizations of their own (to support a greater number of languages). Perhaps these can be kept in a non-signed JAR file (that is, other than rt.jar) that users can add localizations, repackage and easily deploy. Alternatively, perhaps an SPI can be provided to allow users to supply their own runtime localizations.