keys property
Which translation keys produced this node's words, and where.
Empty for a node that draws no text, for text that came from somewhere other than a catalog — a date, a name, a hardcoded literal — and for every node when no catalog was wired up. Absence is never a claim that the text should have had a key; see unkeyedSpans for the other half.
Implementation
final List<InspectKey> keys;