Red mark on JAR icon inside WEB-INF/Lib on Eclipse

Im working on Eclipse Helios Service Release 1. I found unusual red mark on the JAR file icon in War/WEB-INF/Lib/ folder.开发者_如何学Go

Any body knows what does this means?

Take a look in your problems view (may be called markers depending on your version). You should see a message corresponding to the decorator on the jar. If the problem is still not obvious, post back the text of that message here.