remove exp if not set

src/Builder.php

@@ -210,7 +210,7 @@ public function setTTL(?int $ttl): self
      *
      * @return int|null
      */
-    public function getTTL()
+    public function getTTL(): ?int
     {
         return $this->ttl;
     }

src/Claims/DatetimeTrait.php

@@ -102,7 +102,7 @@ public function setLeeway(int $leeway): self
      *
      * @param int|null $period
      */
-    public function setMaxRefreshPeriod($period): self
+    public function setMaxRefreshPeriod(?int $period): self
     {
         $this->maxRefreshPeriod = $period;
 

src/Factory.php

@@ -38,11 +38,16 @@ public static function make(array $claims = [], array $options = []): Payload
             return ClaimFactory::get($key, $value, $options);
         });
 
+        $requiredClaims = Arr::get($options, 'required_claims', []);
+
+        // If the collection doesn't have an exp then remove it from
+        // the required claims.
+        if (! $collection->has('exp')) {
+            $requiredClaims = Arr::except($requiredClaims, ['exp']);
+        }
+
         // Validate the claims
-        $collection = PayloadValidator::check(
-            $collection,
-            Arr::get($options, 'required_claims', [])
-        );
+        $collection = PayloadValidator::check($collection, $requiredClaims);
 
         return new Payload($collection);
     }