java - Why is Intellij showing a cross (x) over the class icon for one of my Java classes?

Question

The icon that IntelliJ (v11.1) usually shows next to Java classes is a blue circle with a C. But for one of my classes this icon has a small "x" in the top left corner. This particular class is in a package with another class, which has just the usual C in a blue circle.

In case it matters, I'm using a Mac.

問題のクラスはAlertsHandlerです。