Summary

New system properties available to configure Unicode Locale Extensions

Problem

In order for users to specify the default Unicode Locale Extensions through the command line option, new system properties which are analogous to "user.language" should be defined.

Solution

Introducing the following new system properties:

• user.extensions
• user.extensions.display
• user.extensions.format

The value for these properties should take the form of BCP47's "extension" (https://tools.ietf.org/html/bcp47):

extension = singleton 1*("-" (2*8alphanum))

The properties will be read at the JVM startup time (Locale class' static initializer) as well as other Locale related system properties (user.language/region/variant). Later alterations to the properties will have no effect. If the specified extension is invalid, it will be ignored.

Specification

Since this enhancement is adding jdk system properties, no specification change is needed.