code: @Override
      public InheritanceEdge createEdge(ClassVertex source, ClassVertex target) {
          if (!target.isInterface()) {
              source.setDirectSuperclass(target);
          }
          return super.createEdge(source, target);
      }
docs: /*
  (non-Javadoc)
  
  @see
  edu.umd.cs.findbugs.graph.AbstractGraph#createEdge(edu.umd.cs.findbugs
  .graph.AbstractVertex, edu.umd.cs.findbugs.graph.AbstractVertex)