Access token can now return a JWT from itself

src/Entities/AccessTokenEntity.php

@@ -2,6 +2,8 @@
 
 namespace League\OAuth2\Server\Entities;
 
+use Lcobucci\JWT\Builder;
+use Lcobucci\JWT\Signer\Rsa\Sha256;
 use League\OAuth2\Server\Entities\Interfaces\AccessTokenEntityInterface;
 use League\OAuth2\Server\Entities\Traits\EntityTrait;
 use League\OAuth2\Server\Entities\Traits\TokenEntityTrait;
@@ -9,4 +11,25 @@ use League\OAuth2\Server\Entities\Traits\TokenEntityTrait;
 class AccessTokenEntity implements AccessTokenEntityInterface
 {
     use EntityTrait, TokenEntityTrait;
+
+    /**
+     * Generate a JWT from the access token
+     *
+     * @param string $pathToPrivateKey
+     *
+     * @return string
+     */
+    public function convertToJWT($pathToPrivateKey)
+    {
+        return (new Builder())
+            ->setAudience($this->getClient()->getIdentifier())
+            ->setId($this->getIdentifier(), true)
+            ->setIssuedAt(time())
+            ->setNotBefore(time())
+            ->setExpiration($this->getExpiryDateTime()->getTimestamp())
+            ->setSubject($this->getUserIdentifier())
+            ->set('scopes', $this->getScopes())
+            ->sign(new Sha256(), new Key($pathToPrivateKey))
+            ->getToken();
+    }
 }

src/Entities/Interfaces/AccessTokenEntityInterface.php

@@ -2,6 +2,16 @@
 
 namespace League\OAuth2\Server\Entities\Interfaces;
 
+use Lcobucci\JWT\Builder;
+
 interface AccessTokenEntityInterface extends TokenInterface
 {
+    /**
+     * Generate a JWT from the access token
+     *
+     * @param string $pathToPrivateKey
+     *
+     * @return string
+     */
+    public function convertToJWT($pathToPrivateKey);
 }