code: private static <T> T withinLocale(final Callable<T> operation, final Locale locale)
      {
          DefaultICUContext ctx = context.get();
          Locale oldLocale = ctx.getLocale();
  
          try
          {
              ctx.setLocale(locale);
              return operation.call();
          } catch (Exception e)
          {
              throw new RuntimeException(e);
          } finally
          {
              ctx.setLocale(oldLocale);
              context.set(ctx);
          }
      }
docs: <p>
  Wraps the given operation on a context with the specified locale.
  </p>
  
  @param operation
  Operation to be performed
  @param locale
  Target locale
  @return Result of the operation