idx property
Idx is the step's 0-based position, assigned by appending: a new step always lands after the last one.
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
int? idx;