buf.append("\"memory\":{");
        buf.append("\"heap\":{");
        append(buf, "used", () -> mem.getHeapUsed().getBytes()).append(',');
        append(buf, "committed", () -> mem.getHeapCommitted().getBytes()).append(',');
        append(buf, "max", () -> mem.getHeapMax().getBytes()).append(',');
        append(buf, "percent", () -> mem.getHeapUsedPercent());
        buf.append("},");