for (Map.Entry<String, String> entry : custom.entrySet()) {
json.writeStringField(entry.getKey(), entry.getValue());
}
json.writeEndObject();
}
json.writeStringField("units", units);
json.writeStringField("dataType", data_type);
json.writeNumberField("retention", retention);
json.writeNumberField("max", max);
json.writeNumberField("min", min);