title: Why does Eclipse Java Package Explorer show question mark on some classes?
body: <p>In the Eclipse Helios Java Package Explorer, I see the Java class icons display a small question mark to the right of the 'J', something like [J?]. This icon is shown on each class within one package in my project, but I cannot find an explanation for this in the documentation. </p>
  
  <p><a href="https://i.stack.imgur.com/kndB6.png"><img src="https://i.stack.imgur.com/kndB6.png" alt="enter image description here"></a></p>
  
  <p>At some point I expect them to disappear and be replaced with small orange rectangles. (Of which I'm also not certain of their meaning, but less worried of their connotation.) I suppose this question points to a larger one, are any of these icons defined together somewhere?</p>