Its a good practice before starting any new project in Oracle ADF to setup framework buffer classes. which acts as a layer between your code and framework.
What JDeveloper Handbook says about it
"Adding your own buffer classes between the application and the framework provides two
benefits. First, as the application evolves, you will identify certain bits of reusable functionality or
functionality that modifies the default way that the framework operates. These can be moved into
the buffer class with a minimum of disruption and immediately become available to all your
classes, since your classes will extend this framework buffer class. Second, the buffer class
provides a good patching point. If you encounter a problem in the way that the base framework
works, you can patch workarounds into the single buffer class, rather than having to make the
change in every implementation"
More details in this video