Double[] visualBreaks = {-1.0, -0.5, 0.0, 0.5, 1.0};
Double[] visualCounts = { 123., 4., 56., 7. };
ObjectMapper objectMapper = new DefaultObjectMapper();
String json = objectMapper.writeValueAsString(h.asVisual());
Map<String,Object> expectedObj = Maps.newLinkedHashMap();
expectedObj.put("breaks", Arrays.asList(visualBreaks));
expectedObj.put("counts", Arrays.asList(visualCounts));
expectedObj.put("quantiles", Arrays.asList(new Double[]{-1.0, 1.0}));