A Capsule Core Nested in a Java Class Leads to a ClassCastException in Proc

[dwtj]

It looks like this is a case which is not yet prevented by our compiler checks:

package issue;

import org.paninij.lang.Capsule;

public class HasNestedCapsule {
    @Capsule class FooCore { }
}

Here is the stack trace.

Caused by: java.lang.ClassCastException: com.sun.tools.javac.code.Symbol$ClassSymbol cannot be cast to javax.lang.model.element.PackageElement
        at org.paninij.proc.model.CapsuleElement.getPackage(CapsuleElement.java:167)
        at org.paninij.proc.factory.CapsuleInterfaceFactory.generateContent(CapsuleInterfaceFactory.java:67)
        at org.paninij.proc.factory.AbstractCapsuleFactory.make(AbstractCapsuleFactory.java:41)
        at org.paninij.proc.RoundZeroProcessor.process(RoundZeroProcessor.java:65)
        at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:794)
        at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:705)
        at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$1800(JavacProcessingEnvironment.java:91)
        at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1035)
        at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1176)
        at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1170)
        at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:856)
        at com.sun.tools.javac.main.Main.compile(Main.java:523)