PDFbox saying PDDocument closed when its not

Question

I am trying to populate repeated forms with PDFbox. I am using a TreeMap and populating the forms with individual records. The format of the pdf form is such that there are si

Answer 1

Even though the above answer was marked as the solution to the problem, since the solution is buried in the comments, I wanted to add this answer at this level. I spent several hours searching for the solution.

My code snippets and comments.

// Collection solely for purpose of preventing premature garbage collection
List sourceDocuments = new ArrayList<>( );

...

// Source document (actually inside a loop)
PDDocument docIn = PDDocument.load( artifactBytes );

// Add document to collection before using it to prevent the problem
sourceDocuments.add( docIn );

// Extract from source document 
PDPage extractedPage = docIn.getPage( 0 );
// Add page to destination document
docOut.addPage( extractedPage );

...

// This was failing with "COSStream has been closed and cannot be read."
// Now it works.
docOut.save( bundleStream );