buf.append("},");
        final Classes classes = jvmStats.getClasses();
        buf.append("\"classes\":{");
        append(buf, "loaded", () -> classes.getLoadedClassCount()).append(',');
        append(buf, "total_loaded", () -> classes.getTotalLoadedClassCount()).append(',');
        append(buf, "unloaded", () -> classes.getUnloadedClassCount());
        buf.append("},");
        append(buf, "uptime", () -> jvmStats.getUptime().getMillis());