presto-benchmark/src/main/java/io/prestosql/benchmark/JsonBenchmarkResultWriter.java/JsonBenchmarkResultWriter/addResults
class JsonBenchmarkResultWriter:    @Override
    public BenchmarkResultHook addResults(Map<String, Long> results)
    {
        requireNonNull(results, "results is null");
        try {
            jsonGenerator.writeStartObject();
            for (Map.Entry<String, Long> entry : results.entrySet()) {
                jsonGenerator.writeNumberField(entry.getKey(), entry.getValue());
            }
            jsonGenerator.writeEndObject();
        }
        catch (IOException e) {
            throw new UncheckedIOException(e);
        }
        return this;
    }