code: protected String getMessage(String contextId, String fieldPath, String[] faceDescriptorProperty) {
          String[] keys = getMessageKeys(contextId, fieldPath, faceDescriptorProperty);
          return getMessageSourceAccessor().getMessage(new DefaultMessageSourceResolvable(keys, null, keys[0]));
      }
docs: Returns the value of the required property of the FieldFace. Delegates to the getMessageKeys for the message key
  generation strategy. This method uses </code>[contextId + "." + ] fieldPath [ + "." + faceDescriptorProperty[0]]</code>
  for the default value