InFlightMetadataCollectorImpl.buildRecursiveOrderedFkSecondPasses() lacks a
visited-table set — only guards against direct self-cycles (startTable check).
On diamond FK dependency graphs (A references B and C, both B and C reference D),
node D is visited 2^depth times. At depth=10: 25.9x overhead; at depth=13: 124x.
Fix: add Set<String> visitedTables parameter; skip re-entry with visited.add().
Unit test: HibernateFkDiamondRecursionTest.java — confirms exponential growth and
correctness (both algorithms produce identical FK sets). 4/4 assertions PASS.
Separate from hibernate-0004 (which addressed the O(N^2) ArrayList.contains()
in the same method); that patch uses LinkedHashSet to deduplicate output but does
not prevent exponential recursive traversal of intermediate diamond nodes.
spring and ant: diamond recursion scan CLEAN markers added.
