We are using pdf.kit for Java to extract annotations from several marked up versions of the same original document and then merging them back into the original, so all reviewers comments are combined. There are several features of annotations that don't appear to export or import correctly:
1. All comments lose the date they were entered and become indeterminate
2. Any Text Box or Text Callout with a new line character, only the last line of text is captured
3. Stamps that are not straight and solid (no opacity) don't appear.
4. Arrows do not show proper arrowheads and line thickness.
5. All replies to comments are separated from their original comments and show up as separate sticky notes near the original
6. All status changes to comments are separated and show up as separate sticky notes at the bottom of the document
7. Checkmarks on comments are lost
8. Opacity changes to comments are lost
9. Audio comments are lost
In addition, if I made the line style of an arrow dashed it caused an error on the import step, and the final pdf gave an error when opening it saying there was an error on the page.
Some of these items are minor (audio for example), but others are quite serious when trying to merge comments. The dates not displaying, the text boxes losing text and the statuses and replies being separated make this very difficult to say it works.
I've attached a file with the Java code used to test this and 4 files. The original clean pdf, the annotated pdf, the fxdf created by the exportAnnotationsXfdf process and the merged pdf created by the importAnnotationsFromXfdf process.
