Third post about the engineering inside an airport slot coordination platform. The first two — lossless schedule repacking and conflict detection with Union-Find — were about algorithms I designed. This one is about a bug I inherited, and about the most misunderstood exception in Java.
The incident
While bringing an abandoned flight-operations service back to life, production threw this at me:
java.lang.IllegalArgumentException: Comparison method violates its general contract!
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