I want to use this API posted by Oracle.
How do I download it ?
That looks like it is part of their application server (now WebLogic). You would need to download that to get it.
First find out what artefact (jar) it belongs to, then you can see if you want to add the entire archive to your project.
Like Capt said, get the server and then see where it is in.
Worst case, if you only want the bounding box stuff, then copy the class.
Read the legal stuff first though!