Hi Gilad,
so I've took a look at the file, checked the adobe specification and
checked the PDTextField code.
Every field need a FieldType (FT). In the signature example I set it to
Sig. For a TextField you should set Tx. Normaly the PDTextbox class
should set it for you, but i doesn't. Can you try to set the FieldType
manual?
COSDictionary textFieldDict = textfield.getDictionary();
textFieldDict.setName(COSName.FT, "Tx");
Hope this helps.
You can also try to show inside the specification [1] chapter: 12.7.3.1
for the general field dictionary and chapter 12.7.4.3 for the TextFields
specification.
Best regards
Thomas
[1] www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/PDF32000_2008.pdf