presto-verifier/src/main/java/io/prestosql/verifier/JsonEventClient.java/JsonEventClient/postEvent
class JsonEventClient:    @Override
    public <T> void postEvent(T event)
    {
        try {
            ByteArrayOutputStream buffer = new ByteArrayOutputStream();
            JsonGenerator generator = factory.createGenerator(buffer, JsonEncoding.UTF8);
            serializer.serialize(event, generator);
            out.println(buffer.toString().trim());
        }
        catch (IOException e) {
            throw new UncheckedIOException(e);
        }
    }