Create a new process. Open Imports in properties panel. Add custom Class in Data Type Imports: " java.util.List<String> " Click Ok, save the process, close and open the process back. Actual result After saving the process an error message is displayed: " An unexpected system error occurred." After opening process back, xml editor is opened because the process cannot be parsed. Expected result After saving the process no error messages are displayed. After opening process back, Process Editor is opened and Imports contains all previously saved values.