code: protected String[] getMessageKeys(String contextId, String fieldPath, String[] faceDescriptorProperties) {
          return getMessageKeyStrategy().getMessageCodes(contextId, fieldPath, faceDescriptorProperties);
      }
docs: Returns an array of message keys that are used to resolve the required property of the FieldFace. The property
  will be resolved from the message source using the returned message keys in order.
  <p>
  Subclasses my override this method to provide an alternative to the default message key generation strategy.