Writing custom properties into the document info dictionary?

[Numpsy]

Hi,

If I open a PDF that has custom properties in its document information dictionary, I can see those in the document properties:

However, when writing a file, I only see the default property set in DocumentInformationBuilder.

So - is there any means to specify custom properties when writing a document?

I wondered if you could use a custom document information builder or something along those lines, but the ToDictionary function is internal so I don't think that would work.

Thanks