The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
Happened as dated, per the source: "Jewel Changi Airport[3] officially opened to the public on Wednesday 17 April 2019."
Wikipedia confirms Jewel Changi Airport's[3] "Soft Opening: 17 April 2019", an exact match to the pin's stored date, with a separate "Official Opening: 18 October 2019" ceremony six months later.
Changi Airport Group's own press release, titled "Jewel Changi Airport Welcomes the World from 17 April 2019" and stored as published 8 March 2019, announces the opening date about five weeks ahead of time - an exact match to the pin's stored 17 April 2019 date, though the page itself could not be fetched (blocked domain) on this attempt.
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