The JAR file ***.jar has no source attachment是咋回事

The JAR file ***.jar has no source attachment是咋回事
最近开始用超图做东西想,按demo写的例子运行后报错,
The JAR file D:SuperMapSuperMapiServerJava6RwebappsiserverWEB-INFlibiserver-all-6.1.0-8304.jar has no source attachment
可是我在项目的JAVA BUILD PATH里面的Libraries里面已经添加了这个Jar包,路径也没错,说没有source attachment是咋回事?还有很多类似这样的,貌似都是这个路径下的