Whether returning false will cancel the write.
true only for a silent re-save to a bound, writable destination — the one case where the
bytes would replace a file that may hold what is about to be lost. See
WriteOptions.onWarnings for why a prompted write cannot be cancelled.
The IWorkbookIO.Origin handle the operation actually used — the file read, or the file written: the workbook's own origin for a plain save, a new one for a save that resolved a destination (a first save, a Save As), the target for an export. Its format is the one read or written.
true for a save (the workbook will be marked clean), false for an export copy.
Every warning the write raised, deduplicated, in the order they were first raised.
The workbook that was read or written. A listener filters on this to react to a specific workbook (the service is shared across all of them).
What WriteOptions.onWarnings is asked to decide on.