org.netbeans.modules.classfile.InvalidClassFormatException
   at org.netbeans.modules.classfile.ClassFile.loadClassHeader(ClassFile.java:207)
Caused: org.netbeans.modules.classfile.InvalidClassFormatException
   at org.netbeans.modules.classfile.ClassFile.load(ClassFile.java:196)
   at org.netbeans.modules.classfile.ClassFile.<init>(ClassFile.java:148)
   at org.netbeans.modules.java.JavaNode$IconTask$ClassIcon.computeIcon(JavaNode.java:528)
   at org.netbeans.modules.java.JavaNode$IconTask.run(JavaNode.java:424)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1423)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)