How to determine if Oracle Java classes are being used Oracle EE 12.1.0.2

As part of a general clean up of a legacy application prior to a migration I'm trying to determine what objects are actually in use.

There are some 230 JAVA class objects in my database.  I can look at DBA_DEPENDENCIES to see where the dependencies between the java classes exist.  I can look at DBA_SOURCE to find what packages  include the phrase 'AS LANGUAGE JAVA' to find packages that wrap JAVA classes. I am auditing the execution of all the packages owned by our application schema.  But as far as I know you can't audit what procedures are called inside of a package.

Is there a way to audit the execution of the java class itself?  Can JAVA classes be called without being wrapped in a PL/SQL procedure?

I'm not a JAVA programmer (if that isn't obvious).
Doc https://docs.oracle.com/database/121/SQLRF/statements_4007.htm#SQLRF01107 for AUDIT statement says "Java schema objects (sources, classes, and resources) are considered the same as procedures for purposes of auditing SQL statements." So I assume that you can audit these Java objects with AUDIT statement (but I have not tested this).