Java Development Tools

I have created a class diagram in JDeveloper 11.1.1.3.0. When I generated java code from the class diagram by right clicking on the class diagram->transform->same diagram->UML to Java, a .java file is generated with attributes and getters/setters, and also a .uml_cla file is generated. What is this .uml_cla file exactly and what is it used for? Also I have a package.uml_pck file that was created 3 times. I have a package of com.xxx.xxxx, and it put this package.uml_pck file in "com", in "xxx", and in "xxxx". Do I need to retain all 3 of these files in my project?

One more question related to this. When I change something in the java representation of the class diagram (i.e. a datatype), it updates the .java file that was generated from the class diagram, and it also works the other way...change the .java file and the java representation of the class diagram changes. However, the class diagram that the code was generated from does not change, nor does the mysterious .uml_cla file I asked about in the above paragraph.