The Structure Parameter Classes 
The structure parameter proxy classes are proxy classes for structure parameters of BAPI methods. They offer setter and getter functions to write to and read from individual fields in the structure parameter, respectively. A field setter function takes data of a Java native type as arguments and sets its corresponding field to that data value. A field getter function returns data value of Java native type, converted from the ABAP data type of the corresponding field of the structure parameter.
See an example of a structure parameter proxy class for a structure parameter of the reference structure type
BAPI0015_2 in the Java BAPI HTML Reference (in Com.sap.bapi.profitcenter.jbobapi0015_2structure.html)Naming convention
The naming convention of the setter and getter of fields is as follows: