code: public void testTaskFormKeyWhenUsingIncludeVariables(){
    deployOneTaskTestProcess();
    runtimeService.startProcessInstanceByKey("oneTaskProcess");
    Task task=taskService.createTaskQuery().singleResult();
    assertNotNull(task);
    Map<String,Object> vars=new HashMap<String,Object>();
    for (int i=0; i < 20; i++) {
      vars.put("var" + i,i * 2);
    }
    taskService.setVariables(task.getId(),vars);
    task=taskService.createTaskQuery().singleResult();
    task.setFormKey("test123");
    taskService.saveTask(task);
    task=taskService.createTaskQuery().includeProcessVariables().singleResult();
    assertEquals(vars.size(),task.getProcessVariables().size());
    assertEquals("test123",task.getFormKey());
  }
  