requestedStableId property
Identity of what was ASKED for vs what was ACTED on — additive keys,
each omitted when null. They let the backend see a redirect / a wrong
element instead of trusting a bare success.
requestedText is the step's target_text (the LABEL asked for —
never the text typed), truncated to kRequestedTextMax chars, and
omitted entirely for an obscured field.
Implementation
final String? requestedStableId;