It would be nice to support special cases for zero items, as in "There are no files." rather than "There are 0 files."
Idea: We don't need to collect CLDR data for the zero case, and we don't need special support for it in PluralRules. The PluralFormat class could detect that the message pattern string defines a case with the "zero" keyword, and if it's there and the number is 0, bypass the PluralRules and select this case directly. If the pattern does not define a zero case, or if the number is not 0, then work as usual.
Instead, we have implemented "extended plurals" with sub-messages for explicit values like "=0". See ticket #7858, implemented as part of ticket #8319.