When debugging and looking at the annotation properties, I can see that the OverlayText has definitely changed. So, I wrote a method that opens a PDF, loops through the pages, then loops through the annotations on each page, and checks if an annotation is a PdfRedactAnnotation.

The PdfRedactAnnotation object has a method called SetOverlayText() that looks like it should do what I want. I am trying to alter the text contained within every redaction annotation in a PDF, using iText7. The desired result is to be able to change the text that appears when applying redactions from 'Original Overlay Text' to any other value, such as 'New Text'. If you need a sample to test with, this DropBox folder has a file called 01 - Original.pdf that you can use as the source document. I've kept my original question and the follow-up with what I've personally tried below.

While I would prefer to use iText7, I will also consider solutions using other libraries that I can reasonably access (I do have a small budget that I could use to purchase another library, if I need to). My original question specified iText7, as that was the library that got me the closest in my own attempts.

I have added a bounty of 150 reputation, as I don't think that I will be able to work out a solution on my own. I don't need to alter the text that is shown in the preview, just what is shown after redactions are applied. It also seems like the preview is maintained separately from the actual redaction that is applied. In my attempts, I have discovered that the 'preview' that is available in Acrobat products when hovering your cursor over a redact box is unique to Acrobat, and most other viewers won't show the preview. The code will be ran prior to the redactions being applied. My goal is to overwrite what was selected by the user with a system defined value. In Acrobat, you can set up a collection of 'redaction codes' that can be used to identify why you are marking something as redacted. I am trying to alter the redaction annotation to change the underlying text that gets burned into a PDF when you apply redactions.

Foxit reader redact