إضافة ووتر مارك watermark on pdf

I want a pure java code

I give it pdf and it add watermarks on it and return it the given pdf after adding the water marks on it

the input to the function is large String base64 contains the pdf

then u can convert base64 to pdf then add water mark then convert it back to base64 and return it

-ملاحظة اريد الكود بدون ما ادفع ترخيص لشركة خارجية لاستخدام الباكج الخاص بهم

الكود يجب ان يعمل بدون انترنت

-note u can use package and import as long as it is free and has no limitans

-the final code should work inside oracle after it is tested on java engouement , I can help in this part

the code should works locally without internet access with no limit to number of use or executions

for ur test u can use this url to convert from base64 to pdf to check the results

https://base64.guru/conve...

where u can convert pdf to base64 to test ur code

https://base64.guru/conve...