code: @Test public void executeValidationShouldNotRiseErrorsForServiceTasksSettingOnlyTheImplementation(){
    Process process=new Process();
    ServiceTask serviceTask=new ServiceTask();
    serviceTask.setImplementation("myImpl");
    process.addFlowElement(serviceTask);
    BpmnModel bpmnModel=new BpmnModel();
    ArrayList<ValidationError> errors=new ArrayList<>();
    validator.executeValidation(bpmnModel,process,errors);
    assertThat(errors).as("No error is expected: the default behavior will be used").isEmpty();
  }
  