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.
findAndVerifyWindowGrace() recurses over parent GraphNodes without a visited
accumulator. Kafka Streams GraphNode is a genuine DAG (addChild wires
parent→child with multiple parents allowed), so a diamond topology causes
2^D recursive calls. Fix: thread an IdentityHashMap<GraphNode,Long> memo
through recursion; memoize on first visit, return cached result on revisit.
8/8 unit tests PASS; D=10 defect count=3071 vs patched O(N).
Diamond-recursion CLEAN markers added for: flink, neo4j, janusgraph,
tinkerpop, dgraph, zookeeper, storm, ant, gradle, graal, eclipse-jdt,
exposed, intellij, kotlin, scala3, hibernate-0007 (prior session work
now committed).
