chore: import upstream snapshot with attribution

tests/fixtures/KafkaPatterns.java

@@ -0,0 +1,47 @@
+package com.example.kafka;
+
+import org.springframework.kafka.annotation.KafkaListener;
+import org.springframework.kafka.annotation.KafkaHandler;
+import org.springframework.kafka.core.KafkaTemplate;
+import org.springframework.kafka.core.KafkaOperations;
+import org.springframework.stereotype.Service;
+import org.springframework.stereotype.Component;
+import lombok.RequiredArgsConstructor;
+import reactor.kafka.receiver.KafkaReceiver;
+
+// ── Annotation-based consumer ─────────────────────────────────────────────
+
+@Service
+class OrderEventConsumer {
+
+    @KafkaListener(topics = "order-events")
+    public void onOrder(String payload) {}
+
+    @KafkaListener(topics = {"order-dlq", "order-retry"})
+    public void onDlq(String payload) {}
+}
+
+// ── Annotation-based producer (KafkaTemplate field) ───────────────────────
+
+@Service
+@RequiredArgsConstructor
+class NotificationProducer {
+    private final KafkaTemplate<String, String> kafkaTemplate;
+    // static field — should NOT produce edge
+    private static final String TOPIC = "notifications";
+}
+
+// ── Reactive consumer (KafkaReceiver field) ───────────────────────────────
+
+@Service
+@RequiredArgsConstructor
+class ReactiveOrderConsumer {
+    private final KafkaReceiver<String, OrderEvent> kafkaReceiver;
+    private final KafkaOperations<String, String> kafkaOps;
+}
+
+// ── plain class with no Kafka ─────────────────────────────────────────────
+
+class OrderEvent {
+    private String id;
+}