The second bullet of the "Compaitibility special cases" section in the method description reads:

"A locale with language "no", country "NO", and variant "NY", representing Norwegian Nynorsk, will be represented as having language "nn", country "NO", and empty variant. This is because some JVMs used the deprecated form to represent the user's default locale, and for compatibility reasons that Take a has not been changed."

This at least includes a typo at the very end, and is sort of cryptic. It should be replaced with something like:

"A locale with language "no", country "NO", and variant "NY", representing Norwegian Nynorsk (Norway) is converted to a language tag "nn-NO"."