According to Yoshito, CLDR has a requirement for supporting shortest representation of localized GMT format in the date time formatting pattern letters. This entry is to track the possible enhancement fix to enable JSR-310 to do the shortest GMT format printing defined in CLDR.
The spec/status in CLDR is not available as of this filing.
This is currently in the requirement stage in the CLDR community. Once the CLDR spec is settled, I suppose JSR-310 can revisit this in the next opportunity to do so.
Has this been fixed by the recent "O" pattern letter and appendLocalizedOffset() ?
Related JBS/bugs.sun.com 8015989
The CLDR ticket is: http://unicode.org/cldr/trac/ticket/5382
Most recently it seems to have been defered to the 25design milestone.
Closing, will track in JBS https://bugs.openjdk.java.net/browse/JDK-8015989