The shape of the resource holding the collection, possibly deferred to break definition cycles
The slice naming the collection property
The shape of the resources the collection embeds, or of the ones its references point to, with inherited members merged in as by eager
TraceError If the shape carries no property by the name the slice states, or if the property collects anything other than resources
Resolves the shape of the drafts posted to a collection property.
Every new item of the collection named by a slice must satisfy this shape. Callers use it to validate a draft before storing it.