Whenever I run a java program normally or in debug mode, in Eclipse, a window pops up saying something of the sort that 'the source attachment does not contain the soruce for the file URLClassLoader.class'.

This is very annoying because I don't understand the problem and at any rate I'm not really interested in the source of the URLClassLoader.class. All I want to do is to get my programming work done without having to close this popup all the time.

How do I get rid of this window?