Summary

Fixes spring-projects#4444.

In KafkaMessageListenerContainer.processCommits(), the if-else if structure caused timedAcks() to be unreachable for COUNT_TIME ack mode:

// BEFORE (broken): isCountAck is true for COUNT_TIME, so timedAcks() is never called
if (this.isCountAck) {
    countAcks();
}
else if (this.isTimeAck) {   // dead code for COUNT_TIME
    timedAcks();
}

For COUNT_TIME, both isCountAck and isTimeAck are true, so timedAcks() was never reached — only the count threshold was ever checked.

Fix

Split into two independent if checks so both conditions are evaluated:

if (this.isCountAck) {
    countAcks();
}
if (this.isTimeAck) {
    timedAcks();
}
else if (!this.isCountAck && !this.isManualImmediateAck) {
    commitIfNecessary();
    this.count = 0;
}

No double-commit risk: when countAcks() fires it resets last = now, so the subsequent timedAcks() call sees elapsed ≈ 0 and skips the commit.

Tests

Added testCountTimeAckModeCommitsOnTimeExpiry — a mock-based test that sets a large ackCount (1000, never reached) and a small ackTime (300 ms), then asserts that commitSync is called within 10 s purely from the time condition being satisfied.

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