code: private static void getWildcardTypePackageNames(WildcardType type,
        Map<String, Class<?>> packageNames) {
      for (Type boundType : type.getUpperBounds()) {
        getTypePackageNames(boundType, packageNames);
      }
  
      for (Type boundType : type.getLowerBounds()) {
        getTypePackageNames(boundType, packageNames);
      }
    }
docs: Visits wildcard types to collect package names.
  
  @see {@link #getTypeVariablePackageNames}.