code: public static String getPackageName(final Class<?> cls) {
          if (cls == null) {
              return StringUtils.EMPTY;
          }
          return getPackageName(cls.getName());
      }
docs: <p>Gets the package name of a {@code Class}.</p>
  
  @param cls  the class to get the package name for, may be {@code null}.
  @return the package name or an empty string