childParentData
Returns the current parent-data value supplied by one direct child's modifier chain.
The query does not measure or place the child and does not mutate retained measurement or placement state. A provider is read only after the complete consecutive chain has been scanned.
Return
the innermost matching provider value, or null when no provider uses key.
Parameters
index
the absolute direct-child index.
key
the referential parent-data token to find.
Throws
when index is outside the direct-child range.
when the callback scope is no longer active or the child scope rejects the access.
when the selected provider fails; the original failure is propagated unchanged.