public function encodeMessageRef(MessageRef $messageRef, Field $field)
    {
        return [
            'M' => [
                'curie' => [self::TYPE_STRING => $messageRef->getCurie()->toString()],
                'id'    => [self::TYPE_STRING => $messageRef->getId()],
                'tag'   => $messageRef->hasTag() ? [self::TYPE_STRING => $messageRef->getTag()] : ['NULL' => true],
            ],
        ];
    }
public function encodeMessageRef(MessageRef $messageRef, Field $field)
    {
        return [
            'M' => [
                'curie' => [self::TYPE_STRING => $messageRef->getCurie()->toString()],
                'id'    => [self::TYPE_STRING => $messageRef->getId()],
                'tag'   => $messageRef->hasTag() ? [self::TYPE_STRING => $messageRef->getTag()] : ['NULL' => true],
            ],
        ];
    }
@param MessageRef $messageRef
@param Field      $field

@return mixed