ExtensionElements extensionElements = addExtensionElements(caseTask);
CamundaIn sourceElement = createElement(extensionElements, null, CamundaIn.class);
sourceElement.setCamundaSourceExpression(source);
// when
CmmnActivity activity = handler.handleElement(planItem, context);
// then
CaseTaskActivityBehavior behavior = (CaseTaskActivityBehavior) activity.getActivityBehavior();
CallableElement callableElement = behavior.getCallableElement();
CallableElementParameter parameter = callableElement.getInputs().get(0);
assertNotNull(parameter);
assertFalse(parameter.isAllVariables());