Hi Sachin,
Those are pl/sql mappings for java stored procedures/functions which Oracle calls it as publishing. Most java developers intend to use java in database under highly computational circumstances rather than data intensive cases.
Here Oracle explains it in key features and
here in detail.
But Oracle also uses java stored procedures and functions too and they encourage java usage in database in the proper way.
Using java to parse a
string or regex operations or xml dom manipulation or array operations or generic sql execution etc... is much more easier in java than to deal with pl/sql. Since java and pl/sql are designed for different purposes. In some ways it is more efficient to use java than pl/sql and sometimes the only option left to programmer.
You should access the java source in order to see what is done inside java code as your scripts are only for publishing. You can search for java source/class with the following query:
Regards,
Fatih.