fix return until full pull request

Author: Falseclock

composer.json

@@ -23,7 +23,9 @@
     "der",
     "binary",
     "encoding",
-    "decoding"
+    "decoding",
+    "gost",
+    "kalkan"
   ],
   "repositories":      [
     {

src/UnsignedAttributes.php

@@ -13,7 +13,6 @@
 use Adapik\CMS\BasicOCSPResponse;
 use Adapik\CMS\CertificateList;
 use Adapik\CMS\Interfaces\CMSInterface;
-use Adapik\CMS\TimeStampToken;
 use Adapik\CMS\UnsignedAttribute;
 use FG\ASN1\Exception\Exception;
 use FG\ASN1\Exception\ParserException;
@@ -89,7 +88,7 @@ public function getRevocationValues()
     /**
      * @return TimeStampToken|CMSInterface|null
      */
-    public function getTimeStampToken(): ?TimeStampToken
+    public function getTimeStampToken()
     {
         return $this->getAttributeAsInstance(TimeStampToken::class);
     }