@Override
    public Optional<Decision> onBufferFinished(int numTotalUnSpillBuffers, int currentPoolSize) {
        return numTotalUnSpillBuffers < numBuffersTriggerSpillingRatio * currentPoolSize
                ? Optional.of(Decision.NO_ACTION)
                : Optional.empty();
    }
@Test
    void testOnBufferFinishedUnSpillBufferBelowThreshold() {
        final int poolSize = 10;
        Optional<Decision> finishedDecision =
                spillStrategy.onBufferFinished(
                        (int) (poolSize * NUM_BUFFERS_TRIGGER_SPILLING_RATIO) - 1, poolSize);
        assertThat(finishedDecision).hasValue(Decision.NO_ACTION);
    }