Every locale a package offers, unioned across all resource roots.
Each root is listed (from its generated contents.json, or by scanning when it has none) and its
entries grouped into locales here.
Union, never first-wins: a user root contributing fr must ADD it rather than replace the shipped
set, and a root overriding one field of de must not drop the rest.
Every locale a package offers, unioned across all resource roots.
Each root is listed (from its generated
contents.json, or by scanning when it has none) and its entries grouped into locales here.Union, never first-wins: a user root contributing
frmust ADD it rather than replace the shipped set, and a root overriding one field ofdemust not drop the rest.