=== SseEmitter.event().data(record, APPLICATION_JSON) ===
{"seq":7,"host":"node-a","cpu":0.42,"heapMb":512,"at":"2026-09-03T10:00:00Z"}
=== SseEmitter.event().data(record)  [no media type] ===
{"seq":7,"host":"node-a","cpu":0.42,"heapMb":512,"at":"2026-09-03T10:00:00Z"}
=== POJO: identical? true ===
=== String payload, no media type   -> {"already":"json"}
=== String payload, APPLICATION_JSON -> {"already":"json"}
=== String payload, APPLICATION_JSON -> {"already":"json"}