When parameters to a method are declared as BY REFERENCE, the default behavior is for any updates to those parameters to be reflected in the corresponding Java objects in the calling Java class on return from the OO COBOL method.
If you do not want the Java objects to be updated, you can set the following static variable:
static boolean mfcobol.runtimeProperties.updateByRefParams;
The default value for this variable is true. Set it to false if you do not want the Java objects to be updated.
Your COBOL development system includes a demonstration program that illustrates the different ways of handling BY REFERENCE parameters.