LikelySubtags and Default Content
First make sure that you do Update Language/Script/Region Subtags first
Run GenerateMaximalLocales with VM argument -DCLDR_DIR set to your cldr directory to generate the likely subtag data AND the default content locales.
If you are trying to debug, add the VM argument -DGenerateMaximalLocalesDebug
Input data:
Data comes from territory/language information in supplemental data.
However, it is supplemented by LANGUAGE_OVERRIDES in GenerateMaximalLocales.java
If there is no territory/language information in supplemental data for a language, add it to LANGUAGE_OVERRIDES.
If the mapping changes when it shouldn't (there are some special cases), add to LANGUAGE_OVERRIDES.
Output:
Creates {CLDR_DIR}/../Generated/cldr/supplemental/likelySubtags.xml and {CLDR_DIR}/../Generated/cldr/supplemental/supplementalMetadata.xml
Diff with {CLDR_DIR}/common/supplemental/likelySubtags.xml and {CLDR_DIR}/common/supplemental/supplementalMetadata.xml
Be very careful to diff everything and check for errors.
Watch especially for backwards incompatible changes; that is, changes rather than just additions.
Look at the above to handle that with LANGUAGE_OVERRIDES.
Run tests, fix input data, and iterate as necessary.
Copy into the svn workspace and commit.