static void serialize(Map<String, Object> m, JsonGenerator g) throws IOException {
            g.writeStartObject();
            for (Map.Entry<String, Object> e : m.entrySet()) {
                g.writeFieldName(e.getKey());
                serializeField(g, e.getValue());
            }
            g.writeEndObject();
        }
Object identity is used to differentiate between different implementation strategies, toString() is used to print a report.

@return an object with a descriptive toString() for the implementation under test
vespajlib/src/test/java/com/yahoo/text/JsonMicroBenchmarkTestCase.java