code: public static Tag exception(Throwable exception) {
  		if (exception != null) {
  			String simpleName = exception.getClass().getSimpleName();
  			return Tag.of("exception", StringUtils.hasText(simpleName) ? simpleName
  					: exception.getClass().getName());
  		}
  		return EXCEPTION_NONE;
  	}
docs: Creates an {@code exception} tag based on the {@link Class#getSimpleName() simple
  name} of the class of the given {@code exception}.
  @param exception the exception, may be {@code null}
  @return the exception tag derived from the exception