code: public void testQueryByAssigneeIds(){
    TaskQuery query=taskService.createTaskQuery().taskAssigneeIds(Arrays.asList(GONZO,KERMIT));
    assertEquals(1,query.count());
    assertEquals(1,query.list().size());
    assertNotNull(query.singleResult());
    query=taskService.createTaskQuery().taskAssigneeIds(Arrays.asList(KERMIT,"kermit2"));
    assertEquals(0,query.count());
    assertEquals(0,query.list().size());
    assertNull(query.singleResult());
    if (processEngineConfiguration.getHistoryLevel().isAtLeast(HistoryLevel.AUDIT)) {
      assertEquals(1,historyService.createHistoricTaskInstanceQuery().taskAssigneeIds(Arrays.asList(GONZO,KERMIT)).count());
      assertEquals(0,historyService.createHistoricTaskInstanceQuery().taskAssigneeIds(Arrays.asList(KERMIT,"kermit2")).count());
    }
    Task adhocTask=taskService.newTask();
    adhocTask.setName("test");
    adhocTask.setAssignee("testAssignee");
    taskService.saveTask(adhocTask);
    query=taskService.createTaskQuery().taskAssigneeIds(Arrays.asList(GONZO,"testAssignee"));
    assertEquals(2,query.count());
    assertEquals(2,query.list().size());
    if (processEngineConfiguration.getHistoryLevel().isAtLeast(HistoryLevel.AUDIT)) {
      assertEquals(2,historyService.createHistoricTaskInstanceQuery().taskAssigneeIds(Arrays.asList(GONZO,"testAssignee")).count());
    }
    taskService.deleteTask(adhocTask.getId(),true);
  }
  