大家好：
线上环境kylin 1.5.4.1版本，在cube详细页的SQL标签页报错，不能正常显示cube的sql语句，后台日志错误信息为：
ERROR [http-bio-8070-exec-2] controller.BasicController:44 :
java.lang.NullPointerException
at
org.apache.kylin.engine.EngineFactory.batchEngine(EngineFactory.java:44)
at
org.apache.kylin.engine.EngineFactory.getJoinedFlatTableDesc(EngineFactory.java:58)
at
org.apache.kylin.rest.controller.CubeController.getSql(CubeController.java:154)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
