private void verifyTopKProbabilityPropertiesControl() {
        VespaModel model = createEnd2EndOneNode(new TestProperties());

        ContentCluster cc = model.getContentClusters().get("storage");
        DispatchConfig.Builder builder = new DispatchConfig.Builder();
        cc.getSearch().getConfig(builder);

        DispatchConfig cfg = new DispatchConfig(builder);
        assertEquals(0.9999, cfg.topKProbability(), 0.0);
    }
Here there is no good choice.
config-model/src/test/java/com/yahoo/vespa/model/content/ContentClusterTest.java