The phrase "white swans" typically refers to something predictable, expected, or likely to happen, similar to seeing a white swan, which is a common occurrence.
Sentences with «white swans»
HOW DOES DEFENSIVE DRIVING ONLINE IN WHITE SWAN Washington WORK? (drivinguniversity.com)
The Avon River at Northam is home to a colony of white swans. (wikiaustralia.com)