docs: public static String getPackageName(Class< ? > clazz,
                                          Package pkg) {
          String pkgName = "";
          if ( pkg == null ) {
              int index = clazz.getName().lastIndexOf( '.' );
              if ( index != -1 ) pkgName = clazz.getName().substring( 0,
                                                                      index );
          } else {
              pkgName = pkg.getName();
          }
          return pkgName;
  
      }