feat(java): detect Spring @EventListener/publishEvent() and emit HANDLES/PUBLISHES edges

[YutenC]

Problem

Spring Application Events create implicit caller-callee relationships invisible to static analysis: a publisher calls publishEvent(new XxxEvent()) and Spring routes it to all @EventListener methods for that event type. CRG had no way to trace this path.

Solution

Two-phase resolution following the existing Spring DI / Temporal patterns:

Parse phase (parser.py):

• @EventListener method → HANDLES edge to virtual event:XxxEvent node
• publishEvent(new XxxEvent()) call → PUBLISHES edge to virtual event:XxxEvent node

Event type is inferred from (in priority order):

1. @EventListener(OrderEvent.class) — explicit annotation arg
2. @EventListener(classes = {A.class, B.class}) — multi-type named arg
3. First method parameter type — implicit / no-arg form

Post-build resolver (event_resolver.py):

• Joins PUBLISHES and HANDLES edges by event_type
• Emits CALLS edges: publisher method → listener method

Usage after this change

# Find all listeners for OrderPlacedEvent
query_graph(callers_of="event:OrderPlacedEvent")

# Find what events a publisher emits
query_graph(callees_of="OrderService.placeOrder")

Changes

• code_review_graph/parser.py — 2 constants + 3 new methods + 2 hooks in _extract_functions
• code_review_graph/event_resolver.py — new post-build resolver
• code_review_graph/incremental.py — _run_event_resolver wired into build pipeline
• tests/fixtures/SpringEvents.java — fixture with publisher + 2 listener patterns
• tests/test_multilang.py — TestSpringEventListenerParsing (6 assertions)