unit property
Unit is the source's own id for the measured unit. With Source it is the key the chart groups by, and the key the board joins a unit's latest reading on.
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? unit;