The content type to get the allowed children of, or null for the root.
The content item the children will be created under, if any.
Optionalpaging: UmbOffsetPaginationRequestModel
The page to return. Implementations must honour this, as a source that ignores it returns the same page repeatedly when a caller pages through the full set.
A promise resolving to { data: { items, total } }, or { error }.
Optionalget
Returns a single page of the content types allowed as children.