使用Activiti5.19.0遇到的一个问题?报错

@咖啡兔 你好，想跟你请教个问题：本人第一次使用activiti,下载了官网最新版本的activiti 5.19.0，在使用中发现流程查询就有问题。代码如下：

TaskService taskService = processEngine.getTaskService();  
        List<Task> taskList = taskService.createTaskQuery().list();

org.apache.ibatis.exceptions.PersistenceException:
### Error querying database.  Cause: java.sql.SQLException: ORA-00936: missing expression

### The error may exist in org/activiti/db/mapping/entity/Task.xml
### The error may involve org.activiti.engine.impl.persistence.entity.TaskEntity.selectTaskByQueryCriteria-Inline
### The error occurred while setting parameters
### SQL: select * from ( select a.*, ROWNUM rnum from (     select distinct RES.*              from ACT_RU_TASK RES                                                                     order by  order by RES.ID_ asc         ) a where ROWNUM < ?) where rnum  >= ?
### Cause: java.sql.SQLException: ORA-00936: missing expression

我定位错误应当在标红位置，sql语句出现2个order by，于是进入activiti源码中org/activiti/db/mapping/entity/Task.xml中selectTaskByQueryCriteria

<select id="selectTaskByQueryCriteria" parameterType="org.activiti.engine.impl.TaskQueryImpl" resultMap="taskResultMap">
    ${limitBefore}
    select distinct RES.* ${limitBetween}
    <include refid="selectTaskByQueryCriteriaSql"/> 
    ${orderBy}
    ${limitAfter}
  </select>

删除${orderBy}后，即可调用正常。请问是我使用错误，还是activiti5.19.0本身的bug呢？

最后附上修改后返回数据成功后截图：