equals-hashcode: equals/hashCode contract demos, missing hashCode and constant-hash costs, mutable keys, records, JPA entity id trap, 13 contract tests

Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b66uwsWr9B1ouyrzUh
2026-11-12 20:08:35 +05:30
parent 319697c345
commit 682b7b067c
22 changed files with 692 additions and 0 deletions
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+== id-based equals/hashCode, id assigned on save ==
+two unsaved entities equal?  true  (both ids null)
+set size after adding two different unsaved entities = 1
+add, then save(): set.contains(c) = false
+
+== constant hashCode ==
+add, then save(): set.contains(d) = true
+
+== natural key, immutable ==
+add, then save(): set.contains(e) = true