protected Map<String, String> coreReportMessage() {
    final Map<String, String> result = new HashMap<>();
    final CachedSubscriptionPollResponse currentResponse = getCurrentResponse();
    result.put(
        "currentResponse",
        Objects.nonNull(currentResponse) ? currentResponse.toString() : "<unknown>");
    return result;
  }
The {@link SubscriptionEventSingleResponse} class represents a single subscription event response
that wraps a cached {@link SubscriptionPollResponse}. The actual payload of the response can be
either a {@link TerminationPayload} or an {@link ErrorPayload}.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/subscription/event/response/SubscriptionEventSingleResponse.java