code: public static String pkgNameOfClassName(String fqClassName) {
          int i = fqClassName.lastIndexOf('.');
          String pkg = i == -1 ? "" : fqClassName.substring(0, i);
          return ":" + pkg;
      }
docs: Extract the package name from a fully qualified class name.
  
  Example: Given "pkg.subpkg.A" this method returns ":pkg.subpkg".
  Given "C" this method returns ":".
  
  @returns package name of the given class name