Can not instance entity

Caused by: com.vtradex.thorn.server.exception.ConfigException: Can not instance entity [com.vtradex.wms.server.model.bc.WmsBcClassesHead]
	at com.vtradex.thorn.server.action.DealParamAction.getMappingValue(DealParamAction.java:502)
	at com.vtradex.thorn.server.action.DealParamAction.convertMappingValue(DealParamAction.java:486)
	at com.vtradex.thorn.server.action.DealParamAction.execute(DealParamAction.java:73)
	... 28 more

 如果是manintain屏，对象没有构造无参构造方法，会报这个错误。对象增加无参构造方法即可。

public WmsBcClassesHead(){

super();

// TODO Auto-generated constructor stub

}