@Test
  public void testOutputSourceExpression() {
    // given:
    String source = "${a}";
    ExtensionElements extensionElements = addExtensionElements(caseTask);
    CamundaOut sourceElement = createElement(extensionElements, null, CamundaOut.class);
    sourceElement.setCamundaSourceExpression(source);

    // when
    CmmnActivity activity = handler.handleElement(planItem, context);

    // then
    CaseTaskActivityBehavior behavior = (CaseTaskActivityBehavior) activity.getActivityBehavior();
    CallableElement callableElement = behavior.getCallableElement();
    CallableElementParameter parameter = callableElement.getOutputs().get(0);

    assertNotNull(parameter);
    assertFalse(parameter.isAllVariables());

    ParameterValueProvider sourceExpressionValueProvider = parameter.getSourceValueProvider();
    assertNotNull(sourceExpressionValueProvider);

    assertTrue(sourceExpressionValueProvider instanceof ElValueProvider);
    ElValueProvider valueProvider = (ElValueProvider) sourceExpressionValueProvider;
    assertEquals(source, valueProvider.getExpression().getExpressionText());
  }
  @Test
  public void testOutputs() {
    // given:
    ExtensionElements extensionElements = addExtensionElements(caseTask);
    CamundaOut variablesElement = createElement(extensionElements, null, CamundaOut.class);
    variablesElement.setCamundaVariables("all");
    CamundaOut sourceElement = createElement(extensionElements, null, CamundaOut.class);
    sourceElement.setCamundaSource("a");
    CamundaOut sourceExpressionElement = createElement(extensionElements, null, CamundaOut.class);
    sourceExpressionElement.setCamundaSourceExpression("${b}");

    // when
    CmmnActivity activity = handler.handleElement(planItem, context);

    // then

    CaseTaskActivityBehavior behavior = (CaseTaskActivityBehavior) activity.getActivityBehavior();
    CallableElement callableElement = behavior.getCallableElement();

    List<CallableElementParameter> outputs = callableElement.getOutputs();
    assertNotNull(outputs);
    assertFalse(outputs.isEmpty());
    assertEquals(3, outputs.size());
  }