Map<String, Object> unknownParams = new HashMap<>();
        unknownParams.put("unknown", new Object());
        assertNull(queryRescorer.evaluate(unknownParams));
    }

    public void test_evaluate_withNestedParams() {
        queryRescorer = new QueryRescorer() {
            @Override
            public RescorerBuilder<?> evaluate(Map<String, Object> params) {
                if (params == null) {