toJson method
Implementation
core.Map<core.String, core.dynamic> toJson() => {
if (data != null) 'data': data!,
if (key != null) 'key': key!,
if (message != null) 'message': message!,
if (severity != null) 'severity': severity!,
if (stateTimestampMillis != null)
'stateTimestampMillis': stateTimestampMillis!,
};