at property
At is when the reading was MEASURED, RFC 3339 in UTC — the x-axis a chart plots against. The series is returned oldest first, so it only increases.
Please note: This property should have been non-nullable! Since the specification file does not include a default value (using the "default:" property), however, the generated source code must fall back to having a nullable type. Consider adding a "default:" property in the specification file to hide this note.
Implementation
String? at;