code: public static Object getDefaultValue(Class<? extends Annotation> annotationType, String attributeName) {
  		if (annotationType == null || !StringUtils.hasLength(attributeName)) {
  			return null;
  		}
  		try {
  			return annotationType.getDeclaredMethod(attributeName).getDefaultValue();
  		}
  		catch (Exception ex) {
  			return null;
  		}
  	}
docs: Retrieve the <em>default value</em> of a named attribute, given the
  {@link Class annotation type}.
  @param annotationType the <em>annotation type</em> for which the default value should be retrieved
  @param attributeName the name of the attribute value to retrieve.
  @return the default value of the named attribute, or {@code null} if not found
  @see #getDefaultValue(Annotation, String)