Plugin descriptor extractor crashes on certain types of Java source files

Part of my plugin includes a .java file that contains an annotation type declaration. It looks like this:

package org.jboss.lang.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.ANNOTATION_TYPE)
public @interface Inherited {
}

When the JavaMojoDescriptorExtractor encounters this file it crashes because of an ArrayIndexOutOfBoundsException. Because the code is trying to access the 1st element of a zero length array. The attached file has a simple fix where the descriptor extractor just ignores any java source file that does not contain a valid class.