of static method
Shared store of document, without a source parser.
Serves whoever only needs to resolve already materialized objects and does not want to rebuild the index on every call — the index stays alive as long as the document exists. Whoever needs the source parser creates their own instance with PdfObjectStore.forDocument.
Implementation
static PdfObjectStore of(PdfDocument document) =>
_shared[document] ??= PdfObjectStore(document);