code: @Test public void testQueryByProcessDefinitionKeyLike(){
    if (processEngineConfiguration.getHistoryLevel().isAtLeast(HistoryLevel.ACTIVITY)) {
      Task task=taskService.createTaskQuery().processDefinitionKeyLike("%\\%%").singleResult();
      assertNull(task);
      task=taskService.createTaskQuery().processDefinitionKeyLike("%\\_%").singleResult();
      assertNull(task);
      task=taskService.createTaskQuery().or().processDefinitionKeyLike("%\\%%").processDefinitionId("undefined").singleResult();
      assertNull(task);
      task=taskService.createTaskQuery().or().processDefinitionKeyLike("%\\_%").processDefinitionId("undefined").singleResult();
      assertNull(task);
    }
  }
  