What is the possessive form of a singular noun ending with a plural s?
This is an area where English usage is very unsettled.
Generally when a proper name ends in s and looks like a plural, it’s at least acceptable to use just the apostrophe without an additional s. Netherlands’s definitely looks odd to me. Since Netherlands is an originally plural word treated as a singular, there’s an especially strong case for not adding the apostrophe-s.
Similarly, I’d say “Lever Brothers’ workers” when talking about the soap company rather than “Lever Brothers’s workers”, even though we'd say “Lever Brothers is” in the US.